Women mourn at graves for miners who died in Tuesday's mine disaster, at a cemetery in Soma, a district in Turkey's western province of Manisa May 20, 2014. The main labour union in a Turkish town hit by the nation's worst mining disaster called on thousands of workers to down tools on Tuesday at mines run by the same operator until the sites have been properly inspected. Three hundred and one miners died last week after a fire in a mine in Soma, a small town 480 km (300 miles) southwest of Istanbul, fuelling anger in a nation which has long had one of the world's worst workplace safety records. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

People mourn at graves for miners who died in Tuesday's mine disaster, at a cemetery in Soma, a district in Turkey's western province of Manisa May 20, 2014. The main labour union in a Turkish town hit by the nation's worst mining disaster called on thousands of workers to down tools on Tuesday at mines run by the same operator until the sites have been properly inspected. Three hundred and one miners died last week after a fire in a mine in Soma, a small town 480 km (300 miles) southwest of Istanbul, fuelling anger in a nation which has long had one of the world's worst workplace safety records. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

A woman mourns at the graves for miners who died in a fire at a coal mine, at a cemetery in Soma, a district in Turkey's western province of Manisa May 20, 2014. The main labour union in a Turkish town hit by the nation's worst mining disaster called on thousands of workers to down tools on Tuesday at mines run by the same operator until the sites have been properly inspected. Three hundred and one miners died last week after a fire in a mine in Soma, a small town 480 km (300 miles) southwest of Istanbul, fuelling anger in a nation which has long had one of the world's worst workplace safety records. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

A woman mourns at graves of miners who died in a fire at a coal mine, at a cemetery in Soma, a district in Turkey's western province of Manisa May 20, 2014. The main labour union in the Turkish town hit by the nation's worst mining disaster called on thousands of workers to down tools on Tuesday at mines run by the same operator until the sites have been properly inspected. Three hundred and one miners died last week after a fire in the mine in Soma, a small town 480 km (300 miles) southwest of Istanbul, fuelling anger in a nation which has long had one of the world's worst workplace safety records. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

A woman mourns at graves of miners who died in a fire at a coal mine, at a cemetery in Soma, a district in Turkey's western province of Manisa May 20, 2014. The main labour union in the Turkish town hit by the nation's worst mining disaster called on thousands of workers to down tools on Tuesday at mines run by the same operator until the sites have been properly inspected. Three hundred and one miners died last week after a fire in the mine in Soma, a small town 480 km (300 miles) southwest of Istanbul, fuelling anger in a nation which has long had one of the world's worst workplace safety records. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

Tamer Kucukgencay, regional head of the Maden-Is labor union, talk to the media in front of the courthouse in Soma, a district in Turkey's western province of Manisa May 20, 2014. The main labor union in the Turkish town hit by the nation's worst mining disaster called on thousands of workers to down tools on Tuesday at mines in the region until the sites had been properly inspected. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

Ramazan Dogru (L), general manager of Soma Mining, arrives at a courthouse in Soma, a district in Turkey's western province of Manisa, May 19, 2014. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

A woman mourns at the graves for miners who died in Tuesday's mine disaster, at a cemetery in Soma, a district in Turkey's western province of Manisa, May 19, 2014. A Turkish court ordered three suspects to be kept in custody on Sunday on a provisional charge of "causing multiple deaths" in last week's mine disaster, as the last of the 301 victims were buried. Of the remaining 22 people detained earlier, six suspects have been released but could face prosecution later. Questioning of the other 16 people was continuing. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

People mourn at the graves for miners who died in Tuesday's mine disaster, at a cemetery in Soma, a district in Turkey's western province of Manisa, May 19, 2014. A Turkish court ordered three suspects to be kept in custody on Sunday on a provisional charge of "causing multiple deaths" in last week's mine disaster, as the last of the 301 victims were buried. Of the remaining 22 people detained earlier, six suspects have been released but could face prosecution later. Questioning of the other 16 people was continuing. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

Women mourn at the graves for miners who died in Tuesday's mine disaster, at a cemetery in Soma, a district in Turkey's western province of Manisa, May 19, 2014. A Turkish court ordered three suspects to be kept in custody on Sunday on a provisional charge of "causing multiple deaths" in last week's mine disaster, as the last of the 301 victims were buried. Of the remaining 22 people detained earlier, six suspects have been released but could face prosecution later. Questioning of the other 16 people was continuing. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

Women mourn at graves for miners who died in Tuesday's mine disaster, at a cemetery in Soma, a district in Turkey's western province of Manisa May 19, 2014. A Turkish court ordered three suspects to be kept in custody on Sunday on a provisional charge of "causing multiple deaths" in last week's mine disaster, as the last of the 301 victims were buried. Of the remaining 22 people detained earlier, six suspects have been released but could face prosecution later. Questioning of the other 16 people was continuing. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

Turkish Army soldiers patrol at the site of a coal mine in Soma, a district in Turkey's western province of Manisa May 19, 2014. A Turkish court ordered three suspects to be kept in custody on Sunday on a provisional charge of "causing multiple deaths" in last week's mine disaster, as the last of the 301 victims were buried. Of the remaining 22 people detained earlier, six suspects have been released but could face prosecution later. Questioning of the other 16 people was continuing. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY MILITARY) 

General view of a mine entrance where a wall has been built, in the western Turkish mining town of Soma, that witnessed a deadly disaster last Tuesday, in Manisa province May 19, 2014. A Turkish court ordered three suspects to be kept in custody on Sunday on a provisional charge of "causing multiple deaths" in last week's mine disaster, as the last of the 301 victims were buried. Of the remaining 22 people detained earlier, six suspects have been released but could face prosecution later. Questioning of the other 16 people was continuing. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

General view of a coal mine site where a fire broke out on Tuesday in Soma, a district in Turkey's western province of Manisa May 18, 2014. Turkish police have detained 18 people, including mining company executives and personnel, as part of an investigation into last week's mine disaster, CNN Turk and other broadcasters reported on Sunday. The rescue operation ended on Saturday after the bodies of the last two workers were carried out, bringing the death toll in Turkey's worst industrial accident to 301. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

Women mourn at graves for miners who died in Tuesday's mine disaster, at a cemetery in Soma, a district in Turkey's western province of Manisa May 18, 2014. Turkish police have detained 18 people, including mining company executives and personnel, as part of an investigation into last week's mine disaster, CNN Turk and other broadcasters reported on Sunday. The rescue operation ended on Saturday after the bodies of the last two workers were carried out, bringing the death toll in Turkey's worst industrial accident to 301. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER) 

People mourn at graves for miners who died in Tuesday's mine disaster, at a cemetery in Soma, a district in Turkey's western province of Manisa May 18, 2014. Turkish police have detained 18 people, including mining company executives and personnel, as part of an investigation into last week's mine disaster, CNN Turk and other broadcasters reported on Sunday. The rescue operation ended on Saturday after the bodies of the last two workers were carried out, bringing the death toll in Turkey's worst industrial accident to 301. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER) 

People mourn at graves for miners who died in Tuesday's mine disaster, at a cemetery in Soma, a district in Turkey's western province of Manisa May 18, 2014. Turkish police have detained 18 people, including mining company executives and personnel, as part of an investigation into last week's mine disaster, CNN Turk and other broadcasters reported on Sunday. The rescue operation ended on Saturday after the bodies of the last two workers were carried out, bringing the death toll in Turkey's worst industrial accident to 301. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER) 

A woman mourns at graves for miners who died in Tuesday's mine disaster, at a cemetery in Soma, a district in Turkey's western province of Manisa May 18, 2014. Turkish police have detained 18 people, including mining company executives and personnel, as part of an investigation into last week's mine disaster, CNN Turk and other broadcasters reported on Sunday. The rescue operation ended on Saturday after the bodies of the last two workers were carried out, bringing the death toll in Turkey's worst industrial accident to 301. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER) 

A woman mourns at graves for miners who died in Tuesday's mine disaster, at a cemetery in Soma, a district in Turkey's western province of Manisa May 18, 2014. Turkish police have detained 18 people, including mining company executives and personnel, as part of an investigation into last week's mine disaster, CNN Turk and other broadcasters reported on Sunday. The rescue operation ended on Saturday after the bodies of the last two workers were carried out, bringing the death toll in Turkey's worst industrial accident to 301. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER) 

People mourn at graves for miners who died in Tuesday's mine disaster, at a cemetery in Soma, a district in Turkey's western province of Manisa May 18, 2014. Turkish police have detained 18 people, including mining company executives and personnel, as part of an investigation into last week's mine disaster, CNN Turk and other broadcasters reported on Sunday. The rescue operation ended on Saturday after the bodies of the last two workers were carried out, bringing the death toll in Turkey's worst industrial accident to 301. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER) 

People mourn at graves for miners who died in Tuesday's mine disaster, at a cemetery in Soma, a district in Turkey's western province of Manisa May 18, 2014. Turkish police have detained 18 people, including mining company executives and personnel, as part of an investigation into last week's mine disaster, CNN Turk and other broadcasters reported on Sunday. The rescue operation ended on Saturday after the bodies of the last two workers were carried out, bringing the death toll in Turkey's worst industrial accident to 301. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER) 

Women mourn near graves for miners who died in Tuesday's mine disaster, at a cemetery in Soma, a district in Turkey's western province of Manisa May 18, 2014. Turkish police have detained 18 people, including mining company executives and personnel, as part of an investigation into last week's mine disaster, CNN Turk and other broadcasters reported on Sunday. The rescue operation ended on Saturday after the bodies of the last two workers were carried out, bringing the death toll in Turkey's worst industrial accident to 301. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER) 

Riot police detain a group of people in Soma, a district in Turkey's western province of Manisa May 17, 2014. Turkish police put the mining town of Soma on virtual lockdown on Saturday, setting up checkpoints and detaining dozens, including lawyers to enforce a ban on protests as rescue efforts following the country's worst industrial disaster ended. The last two bodies of workers thought still to have been left in the mine were carried out four days after a fire sent deadly carbon monoxide through it. That brought the death toll to 301, Energy Minister Taner Yildiz said. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

A group of people, detained by riot police, are seen in a bus in Soma, a district in Turkey's western province of Manisa, May 17, 2014. Turkish police put the mining town of Soma on virtual lockdown on Saturday, setting up checkpoints and detaining dozens, including lawyers to enforce a ban on protests as rescue efforts following the country's worst industrial disaster ended. The last two bodies of workers thought still to have been left in the mine were carried out four days after a fire sent deadly carbon monoxide through it. That brought the death toll to 301, Energy Minister Taner Yildiz said. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

A group of people, detained by riot police, are seen in a bus in Soma, a district in Turkey's western province of Manisa, May 17, 2014. Turkish police put the mining town of Soma on virtual lockdown on Saturday, setting up checkpoints and detaining dozens, including lawyers to enforce a ban on protests as rescue efforts following the country's worst industrial disaster ended. The last two bodies of workers thought still to have been left in the mine were carried out four days after a fire sent deadly carbon monoxide through it. That brought the death toll to 301, Energy Minister Taner Yildiz said. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

Riot police detain a group of people in Soma, a district in Turkey's western province of Manisa, May 17, 2014. Turkish police put the mining town of Soma on virtual lockdown on Saturday, setting up checkpoints and detaining dozens, including lawyers to enforce a ban on protests as rescue efforts following the country's worst industrial disaster ended. The last two bodies of workers thought still to have been left in the mine were carried out four days after a fire sent deadly carbon monoxide through it. That brought the death toll to 301, Energy Minister Taner Yildiz said. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

General view of the coal mine site in Soma, a district in Turkey's western province of Manisa May 17, 2014. Rescue workers began winding up their operations on Saturday after finding the bodies of two more miners, believed to be the last remaining in the mine, bringing the death toll in Turkey's worst industrial disaster to 301, the energy minister said. REUTERS/ Osman Orsal (TURKEYDISASTER - Tags: DISASTER ENERGY) 

Miners work in front of the coal mine in Soma, a district in Turkey's western province of Manisa, after a coal mine explosion May 17, 2014. Rescue workers began winding up their operations on Saturday after finding the bodies of two more miners, believed to be the last remaining in the mine, bringing the death toll in Turkey's worst industrial disaster to 301, the energy minister said. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

General view of the coal mine site in Soma, a district in Turkey's western province of Manisa May 17, 2014. Rescue workers began winding up their operations on Saturday after finding the bodies of two more miners, believed to be the last remaining in the mine, bringing the death toll in Turkey's worst industrial disaster to 301, the energy minister said. REUTERS/ Osman Orsal (TURKEYDISASTER - Tags: DISASTER ENERGY) 

Miners rests in front of the coal mine in Soma, a district in Turkey's western province of Manisa, after a coal mine explosion May 17, 2014. Rescue workers began winding up their operations on Saturday after finding the bodies of two more miners, believed to be the last remaining in the mine, bringing the death toll in Turkey's worst industrial disaster to 301, the energy minister said. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

A miner waits in front of the coal mine in Soma, a district in Turkey's western province of Manisa, after a coal mine explosion, May 17, 2014. Rescue workers began winding up their operations on Saturday after finding the bodies of two more miners, believed to be the last remaining in the mine, bringing the death toll in Turkey's worst industrial disaster to 301, the energy minister said. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

Rescuers walk towards a coal mine in Soma, a district in Turkey's western province of Manisa, after a coal mine explosion, May 17, 2014. Rescue workers began winding up their operations on Saturday after finding the bodies of two more miners, believed to be the last remaining in the mine, bringing the death toll in Turkey's worst industrial disaster to 301, the energy minister said. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

A body of miner is carried to an ambulance in Soma, a district in Turkey's western province of Manisa, late May 16, 2014. The death toll in this week's mining accident in western Turkey is unlikely to be more than 302 people, Turkey's Energy Minister Taner Yildiz said on Friday. A maximum of 18 people are still in the coal mine, Yildiz told reporters in televised comments on the country's deadliest ever mine disaster. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

A body of miner is carried to an ambulance in Soma, a district in Turkey's western province of Manisa, late May 16, 2014. The death toll in this week's mining accident in western Turkey is unlikely to be more than 302 people, Turkey's Energy Minister Taner Yildiz said on Friday. A maximum of 18 people are still in the coal mine, Yildiz told reporters in televised comments on the country's deadliest ever mine disaster. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

A body of miner is carried to an ambulance in Soma, a district in Turkey's western province of Manisa, late May 16, 2014. The death toll in this week's mining accident in western Turkey is unlikely to be more than 302 people, Turkey's Energy Minister Taner Yildiz said on Friday. A maximum of 18 people are still in the coal mine, Yildiz told reporters in televised comments on the country's deadliest ever mine disaster. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

A body of miner is carried to an ambulance in Soma, a district in Turkey's western province of Manisa, late May 16, 2014. The death toll in this week's mining accident in western Turkey is unlikely to be more than 302 people, Turkey's Energy Minister Taner Yildiz said on Friday. A maximum of 18 people are still in the coal mine, Yildiz told reporters in televised comments on the country's deadliest ever mine disaster. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

A body of miner is carried to an ambulance in Soma, a district in Turkey's western province of Manisa, late May 16, 2014. The death toll in this week's mining accident in western Turkey is unlikely to be more than 302 people, Turkey's Energy Minister Taner Yildiz said on Friday. A maximum of 18 people are still in the coal mine, Yildiz told reporters in televised comments on the country's deadliest ever mine disaster. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

Protesters march as they demonstrate to blame the ruling AK Party (AKP) government for the mining disaster in Soma, a district in Turkey's western province of Manisa May 16, 2014. Turkish police fired water cannon and tear gas on Friday to disperse a crowd of several thousand protesters in the town of Soma, where close to 300 people died in the country's worst ever mining disaster this week, a Reuters witness said. The sign reads, "No coal can warm the children of fathers who died in the mine". REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY CIVIL UNREST POLITICS) 

Police use water cannons against protesters as they demonstrate to blame the ruling AK Party (AKP) government for the mining disaster in Soma, a district in Turkey's western province of Manisa May 16, 2014. Turkish police fired water cannon and tear gas on Friday to disperse a crowd of several thousand protesters in the town of Soma, where close to 300 people died in the country's worst ever mining disaster this week, a Reuters witness said. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY CIVIL UNREST POLITICS) 

Police use water cannons against protesters as they demonstrate to blame the ruling AK Party (AKP) government for the mining disaster in Soma, a district in Turkey's western province of Manisa May 16, 2014. Turkish police fired water cannon and tear gas on Friday to disperse a crowd of several thousand protesters in the town of Soma, where close to 300 people died in the country's worst ever mining disaster this week, a Reuters witness said. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY CIVIL UNREST POLITICS) 

Police use water cannons against protesters as they demonstrate to blame the ruling AK Party (AKP) government for the mining disaster in Soma, a district in Turkey's western province of Manisa May 16, 2014. Turkish police fired water cannon and tear gas on Friday to disperse a crowd of several thousand protesters in the town of Soma, where close to 300 people died in the country's worst ever mining disaster this week, a Reuters witness said. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY CIVIL UNREST POLITICS) 

Muslim men pray during Friday prayers in Soma, a district in Turkey's western province of Manisa May 16, 2014. The operator of a Turkish mine in which 284 people died this week and 18 remain trapped said on Friday the exact cause of a fire was still unclear but that a build-up of heat had caused a partial collapse in the plant. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY RELIGION) 

Muslim men pray during Friday prayers in Soma, a district in Turkey's western province of Manisa May 16, 2014. The operator of a Turkish mine in which 284 people died this week and 18 remain trapped said on Friday the exact cause of a fire was still unclear but that a build-up of heat had caused a partial collapse in the plant. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY RELIGION) 

Relatives of a miner mourn beside his grave after a mining disaster in Soma, a district in Turkey's western province of Manisa May 16, 2014. The operator of a Turkish mine in which 284 people died this week and 18 remain trapped said on Friday the exact cause of a fire was still unclear but that a build-up of heat had caused a partial collapse in the plant. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

Relatives of a miner mourn beside his grave after a mining disaster in Soma, a district in Turkey's western province of Manisa May 16, 2014. The operator of a Turkish mine in which 284 people died this week and 18 remain trapped said on Friday the exact cause of a fire was still unclear but that a build-up of heat had caused a partial collapse in the plant. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

Miners rest during a break from their search and rescue operation for their colleagues trapped in a coal mine after a mining disaster in Soma, a district in Turkey's western province of Manisa May 16, 2014. The operator of a Turkish mine in which 284 people died this week and 18 remain trapped said on Friday the exact cause of a fire was still unclear but that a build-up of heat had caused a partial collapse in the plant. Rescuers were still trying to reach parts of the coal mine in Soma, 480 km (300 miles) southwest of Istanbul, three days after a fire knocked out power and shut down the ventilation shafts and elevators, trapping hundreds underground in Turkey's worst ever mining disaster. REUTERS/Stringer (TURKEY - Tags: DISASTER ENERGY) 

Relatives of a miner mourn beside his grave after a mining disaster in Soma, a district in Turkey's western province of Manisa May 16, 2014. The operator of a Turkish mine in which 284 people died this week and 18 remain trapped said on Friday the exact cause of a fire was still unclear but that a build-up of heat had caused a partial collapse in the plant. Rescuers were still trying to reach parts of the coal mine in Soma, 480 km (300 miles) southwest of Istanbul, three days after a fire knocked out power and shut down the ventilation shafts and elevators, trapping hundreds underground in Turkey's worst ever mining disaster. REUTERS/Stringer (TURKEY - Tags: DISASTER ENERGY) 

Miners walk towards a mine to take part in search and rescue operation for their colleagues trapped in a coal mine after a mining disaster in Soma, a district in Turkey's western province of Manisa May 16, 2014. The operator of a Turkish mine in which 284 people died this week and 18 remain trapped said on Friday the exact cause of a fire was still unclear but that a build-up of heat had caused a partial collapse in the plant. Rescuers were still trying to reach parts of the coal mine in Soma, 480 km (300 miles) southwest of Istanbul, three days after a fire knocked out power and shut down the ventilation shafts and elevators, trapping hundreds underground in Turkey's worst ever mining disaster. REUTERS/Stringer (TURKEY - Tags: DISASTER ENERGY) 

Soma Holding Chairman Alp Gurkan talks during a news conference in Soma, a district in Turkey's western province of Manisa May 16, 2014. The operator of a Turkish mine in which 284 people died this week and 18 remain trapped said on Friday the exact cause of a fire was still unclear but that a build-up of heat had caused a partial collapse in the plant. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY BUSINESS HEADSHOT) 

Soma Holding Chairman Alp Gurkan talks during a news conference in Soma, a district in Turkey's western province of Manisa, after a coal mine explosion May 16, 2014. The operator of a Turkish mine in which 284 people died this week and 18 remain trapped said on Friday the exact cause of a fire was still unclear but that a build-up of heat had caused a partial collapse in the plant. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY BUSINESS HEADSHOT) 

A miner talk with relatives of miners in front of the coal mine after a mine explosion in Soma, a district in Turkey's western province of Manisa May 16, 2014. The operator of a Turkish mine in which 284 people died this week and 18 remain trapped said on Friday the exact cause of a fire was still unclear but that a build-up of heat had caused a partial collapse in the plant. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

Rescuers walk towards a coal mine after a mine explosion in Soma, a district in Turkey's western province of Manisa May 16, 2014. The operator of a Turkish mine in which 284 people died this week and 18 remain trapped said on Friday the exact cause of a fire was still unclear but that a build-up of heat had caused a partial collapse in the plant. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

Rescuers wait in front of the coal mine after a mine explosion in Soma, a district in Turkey's western province of Manisa May 16, 2014. The operator of a Turkish mine in which 284 people died this week and 18 remain trapped said on Friday the exact cause of a fire was still unclear but that a build-up of heat had caused a partial collapse in the plant. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

Rescuers wait in front of the coal mine after a mine explosion in Soma, a district in Turkey's western province of Manisa May 16, 2014. The operator of a Turkish mine in which 284 people died this week and 18 remain trapped said on Friday the exact cause of a fire was still unclear but that a build-up of heat had caused a partial collapse in the plant. REUTERS/Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

Miners rest in front of the coal mine after a mine explosion in Soma, a district in Turkey's western province of Manisa May 16, 2014. The operator of a Turkish mine in which 284 people died this week and 18 remain trapped said on Friday the exact cause of a fire was still unclear but that a build-up of heat had caused a partial collapse in the plant. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

Rescuers walk towards a coal mine site after a mine explosion in Soma, a district in Turkey's western province of Manisa May 16, 2014. The operator of a Turkish mine in which 284 people died this week and 18 remain trapped said on Friday the exact cause of a fire was still unclear but that a build-up of heat had caused a partial collapse in the plant. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

A relative of miners waits in front of the coal mine after a mine explosion in Soma, a district in Turkey's western province of Manisa May 16, 2014. The operator of a Turkish mine in which 284 people died this week and 18 remain trapped said on Friday the exact cause of a fire was still unclear but that a build-up of heat had caused a partial collapse in the plant. REUTERS/ Osman Orsal (TURKEY - Tags: DISASTER ENERGY) 

People pray during a funeral at a cemetery after a mining disaster in Soma, a district in Turkey's western province of Manisa May 15, 2014. Rescuers were still trying to reach parts of the coal mine in Soma, 480 km (300 miles) southwest of Istanbul, almost 48 hours after fire knocked out power and shut down the ventilation shafts and elevators, trapping hundreds underground. At least 282 people have been confirmed dead, mostly from carbon monoxide poisoning, and hopes are fading of pulling out any more alive of the 100 or so still thought to be inside. REUTERS/Stringer (TURKEY - Tags: DISASTER ENERGY TPX IMAGES OF THE DAY)