Firefighters stand amongst wreckage at the Buncefield fuel depot in Hemel Hempstead near London December 14, 2005. Safety inspectors said on Wednesday they would begin an investigation into the cause of a massive blaze at the Buncefield oil depot north of London now that fire crews had quenched the flames. Fire crews worked day and night to quench the inferno at the depot near the town of Hemel Hempstead that sent a pall of black smoke high into the sky, casting a shadow across a swathe of southern England. REUTERS/Toby Melville 

A firefighter rests on a wall in front of a collapsed tank at the Buncefield fuel depot in Hemel Hempstead near London, December 14, 2005. Safety inspectors said on Wednesday they would begin an investigation into the cause of a massive blaze at the Buncefield oil depot north of London now that fire crews had quenched the flames. Fire crews worked day and night to quench the inferno at the depot near the town of Hemel Hempstead that sent a pall of black smoke high into the sky, casting a shadow across a swathe of southern England. REUTERS/Toby Melville 

Police officers wear respiratory masks near the Buncefield oil depot in Hemel Hempstead, southeast England December 14, 2005. A blaze reignited at the oil depot early on Wednesday but fire-fighters said they were allowing it burn itself out to prevent the risk of explosion. REUTERS/Toby Melville 

A police officer wears a respiratory mask near the Buncefield oil depot in Hemel Hempstead, southeast England December 14, 2005. A blaze reignited at the oil depot early on Wednesday but fire-fighters said they were allowing it burn itself out to prevent the risk of explosion. REUTERS/Toby Melville 

A police officer wears a respiratory mask whilst guarding damaged buildings near the Buncefield oil depot in Hemel Hempstead, southeast England December 14, 2005. A blaze reignited at the oil depot early on Wednesday but fire-fighters said they were allowing it burn itself out to prevent the risk of explosion. REUTERS/Toby Melville 

A burnt-out car sits in a car-park on the Maylands industrial park by the Buncefield fuel depot at Hemel Hempstead near London on December 14, 2005. Safety inspectors said on Wednesday they would begin an investigation into the cause of a massive blaze at the Buncefield oil depot north of London now that fire crews had quenched the flames. REUTERS/Chris Radburn/Pool/PA 

Men clear broken glass at business offices on the Maylands industrial park by the Buncefield fuel depot at Hemel Hempstead near London December 14, 2005. Safety inspectors said on Wednesday they would begin an investigation into the cause of a massive blaze at the Buncefield oil depot north of London now that fire crews had quenched the flames. Business owners on the industrial park were returning on Wednesday to their premises to assess the aftermath left by Sunday's explosions. REUTERS/Chris Radburn/Pool/PA 

Foam sits on a pool of water around a burnt-out collapsed tank at the Buncefield fuel depot in Hemel Hempstead near London, December 14, 2005. Safety inspectors said on Wednesday they would begin an investigation into the cause of a massive blaze at the Buncefield oil depot north of London now that fire crews had quenched the flames. Fire crews worked day and night to quench the inferno at the depot near the town of Hemel Hempstead that sent a pall of black smoke high into the sky, casting a shadow across a swathe of southern England. REUTERS/Toby Melville 

Firefighters (R) stand amongst wreckage at the Buncefield fuel depot in Hemel Hempstead near London December 14, 2005. Safety inspectors said on Wednesday they would begin an investigation into the cause of a massive blaze at the Buncefield oil depot north of London now that fire crews had quenched the flames. Fire crews worked day and night to quench the inferno at the depot near the town of Hemel Hempstead that sent a pall of black smoke high into the sky, casting a shadow across a swathe of southern England. REUTERS/Toby Melville 

A chicken walks past a wrecked caravan near the Buncefield fuel depot in Hemel Hempstead near London December 14, 2005. Safety inspectors said on Wednesday they would begin an investigation into the cause of a massive blaze at the Buncefield oil depot north of London now that fire crews had quenched the flames. Fire crews worked day and night to quench the inferno at the depot near the town of Hemel Hempstead that sent a pall of black smoke high into the sky, casting a shadow across a swathe of southern England. REUTERS/Toby Melville 

Wreckage smoulders at the Buncefield fuel depot in Hemel Hempstead near London December 14, 2005. Safety inspectors said on Wednesday they would begin an investigation into the cause of a massive blaze at the Buncefield oil depot north of London now that fire crews had quenched the flames. Fire crews worked day and night to quench the inferno at the depot near the town of Hemel Hempstead that sent a pall of black smoke high into the sky, casting a shadow across a swathe of southern England. REUTERS/Toby Melville 

A firefighter rests on a wall in front of collapsed tanks at the Buncefield fuel depot in Hemel Hempstead near London December 14, 2005. Safety inspectors said on Wednesday they would begin an investigation into the cause of a massive blaze at the Buncefield oil depot north of London now that fire crews had quenched the flames. Fire crews worked day and night to quench the inferno at the depot near the town of Hemel Hempstead that sent a pall of black smoke high into the sky, casting a shadow across a swathe of southern England. REUTERS/Toby Melville 

Foam sits on water around tanks at the Buncefield fuel depot in Hemel Hempstead near London December 14, 2005. Safety inspectors said on Wednesday they would begin an investigation into the cause of a massive blaze at the Buncefield oil depot north of London now that fire crews had quenched the flames. Fire crews worked day and night to quench the inferno at the depot near the town of Hemel Hempstead that sent a pall of black smoke high into the sky, casting a shadow across a swathe of southern England. REUTERS/Toby Melville 

A firefighter rests on a wall in front of a collapsed tank at the Buncefield fuel depot in Hemel Hempstead near London, December 14, 2005. Safety inspectors said on Wednesday they would begin an investigation into the cause of a massive blaze at the Buncefield oil depot north of London now that fire crews had quenched the flames. Fire crews worked day and night to quench the inferno at the depot near the town of Hemel Hempstead that sent a pall of black smoke high into the sky, casting a shadow across a swathe of southern England. REUTERS/Toby Melville 

A police officer wears a respiratory mask near the Buncefield oil depot in Hemel Hempstead, southeast England December 14, 2005. A blaze reignited at the oil depot early on Wednesday but fire-fighters said they were allowing it burn itself out to prevent the risk of explosion. REUTERS/Toby Melville 

Smoke continues to rise from the Buncefield oil depot in Hemel Hempstead, southeast England December 14, 2005. A blaze reignited at the oil depot early on Wednesday but fire-fighters said they were allowing it burn itself out to prevent the risk of explosion. REUTERS/Toby Melville 

An insurance assessor walks around damaged buildings near the Buncefield oil depot in Hemel Hempstead, southeast England December 14, 2005. A blaze reignited at the oil depot early on Wednesday but fire-fighters said they were allowing it burn itself out to prevent the risk of explosion. REUTERS/Toby Melville 

An insurance assessor walks around damaged buildings near the Buncefield oil depot in Hemel Hempstead, southeast England December 14, 2005. A blaze reignited at the oil depot early on Wednesday but fire-fighters said they were allowing it burn itself out to prevent the risk of explosion. REUTERS/Toby Melville 

A police handout photograph released on December 13, 2005 shows firemen directing foam onto burning fires at the Buncefield fuel depot in Hemel Hempstead near London on December 12, 2005. Safety inspectors said on Wednesday they would begin an investigation into the cause of a massive blaze at the Buncefield oil depot north of London now that fire crews had quenched the flames. Business owners on the industrial park were returning on Wednesday to their premises to assess the aftermath left by Sunday's explosions. Picture taken December 12, 2005. REUTERS/Chiltern Air Support Unit/Handout 

A police handout photograph released on December 13, 2005 shows a wrecked office complex near the Buncefield fuel depot in Hemel Hempstead near London on December 12, 2005. Safety inspectors said on Wednesday they would begin an investigation into the cause of a massive blaze at the Buncefield oil depot north of London now that fire crews had quenched the flames. Business owners on the industrial park were returning on Wednesday to their premises to assess the aftermath left by Sunday's explosions. Picture taken December 12, 2005. REUTERS/Chiltern Air Support Unit/Handout 

A police handout photograph released on December 13, 2005 shows firemen directing foam onto burning fires at the Buncefield fuel depot in Hemel Hempstead near London on December 12, 2005. Safety inspectors said on Wednesday they would begin an investigation into the cause of a massive blaze at the Buncefield oil depot north of London now that fire crews had quenched the flames. Business owners on the industrial park were returning on Wednesday to their premises to assess the aftermath left by Sunday's explosions. Picture taken December 12, 2005. REUTERS/Chiltern Air Support Unit/Handout 

A police handout photograph released on December 13, 2005 shows firemen directing foam onto burning fires at the Buncefield fuel depot in Hemel Hempstead near London on December 12, 2005. Safety inspectors said on Wednesday they would begin an investigation into the cause of a massive blaze at the Buncefield oil depot north of London now that fire crews had quenched the flames. Business owners on the industrial park were returning on Wednesday to their premises to assess the aftermath left by Sunday's explosions. Picture taken December 12, 2005. REUTERS/Chiltern Air Support Unit/Handout 

Burnt trees stand near one of the exploded fuel storage tanks at the Buncefield oil depot in Hemel Hempstead, Hertfordshire, southeast England December 13, 2005. Firefighters pumping masses of water and foam onto a major fire at a fuel depot north of London hope to extinguish the blaze completely later on Tuesday. Fire crews worked through the night on the inferno -- described by officials as the largest of its type in peacetime Europe -- which broke out on Sunday morning near the town of Hemel Hempstead. REUTERS/Stefan Rousseau/Pool 

Damaged buildings lie empty near the Buncefield oil depot in Hemel Hempstead, Hertfordshire, southeast England, December 13, 2005. Fire crews made further progress overnight in extinguishing a massive blaze at a fuel depot north of London, a fire service spokeswoman said on Tuesday. REUTERS/Stefan Rousseau/PA Pool 

Damaged buildings lie empty near the Buncefield oil depot in Hemel Hempstead, Hertfordshire in southeast England, December 13, 2005. Firefighters pumping masses of water and foam onto a major fire at a fuel depot north of London hope to extinguish the blaze completely later on Tuesday. Fire crews worked through the night on the inferno -- described by officials as the largest of its type in peacetime Europe -- which broke out on Sunday morning near the town of Hemel Hempstead. REUTERS/Stefan Rousseau/PA Pool 

Burnt trees stand near one of the exploded fuel storage tanks at the Buncefield oil depot in Hemel Hempstead, Hertfordshire, southeast England December 13, 2005. Firefighters pumping masses of water and foam onto a major fire at a fuel depot north of London hope to extinguish the blaze completely later on Tuesday. Fire crews worked through the night on the inferno -- described by officials as the largest of its type in peacetime Europe -- which broke out on Sunday morning near the town of Hemel Hempstead. REUTERS/Stefan Rousseau/PA Pool 

Firefighters hose one of the fuel storage tanks at the Buncefield oil depot in Hemel Hempstead, Hertfordshire in southeast England December 13, 2005 as they continue to fight the blaze which has been raging for more than 48 hours. Firefighters pumping masses of water and foam onto a major fire at a fuel depot north of London hope to extinguish the blaze completely later on Tuesday. Fire crews worked through the night on the inferno -- described by officials as the largest of its type in peacetime Europe -- which broke out on Sunday morning near the town of Hemel Hempstead. REUTERS/Stefan Rousseau/PA Pool 

One of the fuel storage tanks at the Buncefield oil depot in Hemel Hempstead, Hertfordshire, southeast England December 13, 2005 is hosed by firefighters as they continue to fight the blaze which has been raging for more than 48 hours. Firefighters pumping masses of water and foam onto a major fire at a fuel depot north of London hope to extinguish the blaze completely later on Tuesday. Fire crews worked through the night on the inferno -- described by officials as the largest of its type in peacetime Europe -- which broke out on Sunday morning near the town of Hemel Hempstead. REUTERS/Stefan Rousseau/PA Pool 

Firefighters take a break after tackling the blaze at the Buncefield oil depot in Hemel Hempstead, Hertfordshire, southeast England, December 13, 2005. Firefighters pumping masses of water and foam onto a major fire at a fuel depot north of London hope to extinguish the blaze completely later on Tuesday. Fire crews worked through the night on the inferno -- described by officials as the largest of its type in peacetime Europe -- which broke out on Sunday morning near the town of Hemel Hempstead. REUTERS/Stefan Rousseau/PA Pool 

Firefighters look at one of the fuel storage tanks at the Buncefield oil depot in Hemel Hempstead, Hertfordshire, southeast England as they continue to fight the blaze which has been raging for more than 48 hours, December 13, 2005. Fire crews made further progress overnight in extinguishing a massive blaze at a fuel depot north of London, a fire service spokeswoman said on Tuesday. REUTERS/Stefan Rousseau/PA Pool 

One of the fuel storage tanks at the Buncefield oil depot in Hemel Hempstead, Hertfordshire, southeast England is hosed by firefighters as they continue to fight the blaze which has been raging for more than 48 hours, December 13, 2005. Fire crews made further progress overnight in extinguishing a massive blaze at a fuel depot north of London, a fire service spokeswoman said on Tuesday. REUTERS/Stefan Rousseau/PA Pool 

One of the fuel storage tanks at the Buncefield oil depot in Hemel Hempstead, Hertfordshire, southeast England is hosed by firefighters as they continue to fight the blaze which has been raging for more than 48 hours, December 13, 2005. Fire crews made further progress overnight in extinguishing a massive blaze at a fuel depot north of London, a fire service spokeswoman said on Tuesday. REUTERS/Stefan Rousseau/PA Pool 

One of the fuel storage tanks at the Buncefield oil depot in Hemel Hempstead, Hertfordshire, southeast England is hosed by firefighters as they continue to fight the blaze which has been raging for more than 48 hours, December 13, 2005, Fire crews made further progress overnight in extinguishing a massive blaze at a fuel depot north of London, a fire service spokeswoman said on Tuesday. REUTERS/Stefan Rousseau/PA/WPA Pool 

Damaged buildings lie empty near the Buncefield oil depot in Hemel Hempstead, Hertfordshire in southeast England, December 13, 2005. Firefighters pumping masses of water and foam onto a major fire at a fuel depot north of London hope to extinguish the blaze completely later on Tuesday. Fire crews worked through the night on the inferno -- described by officials as the largest of its type in peacetime Europe -- which broke out on Sunday morning near the town of Hemel Hempstead. REUTERS/Stefan Rousseau/PA Pool 

Police guard against looters at the scene on an industrial estate next to the Buncefield oil depot in Hemel Hempstead, Hertfordshire southeast England, December 13, 2005. Firefighters pumping masses of water and foam onto a major fire at a fuel depot north of London hope to extinguish the blaze completely later on Tuesday. Fire crews worked through the night on the inferno -- described by officials as the largest of its type in peacetime Europe -- which broke out on Sunday morning near the town of Hemel Hempstead. REUTERS/Stefan Rousseau/PA Pool 

One of the fuel storage tanks at the Buncefield oil depot in Hemel Hempstead, Hertfordshire, southeast England is hosed by firefighters as they continue to fight the blaze which has been raging for more than 48 hours, December 13, 2005. Fire crews made further progress overnight in extinguishing a massive blaze at a fuel depot north of London, a fire service spokeswoman said on Tuesday. REUTERS/Stefan Rousseau/PA/WPA Pool 

One of the fuel storage tanks at the Buncefield oil depot in Hemel Hempstead, Hertfordshire, southeast England is hosed by firefighters as they continue to fight the blaze which has been raging for more than 48 hours, December 13, 2005. Fire crews made further progress overnight in extinguishing a massive blaze at a fuel depot north of London, a fire service spokeswoman said on Tuesday. REUTERS/Stefan Rousseau/PA Pool 

Smoke billows on the third day of the fire from the Buncefield oil depot in Hemel Hempstead, southeast England December 13, 2005. Firefighters pumping masses of water and foam onto a major fire at a fuel depot north of London hope to extinguish the blaze completely later on Tuesday. REUTERS/Paul Hackett 

One of the fuel storage tanks at the Buncefield oil depot in Hemel Hempstead, Hertfordshire, southeast England is hosed by firefighters as they continue to fight the blaze which has been raging for more than 48 hours, December 13, 2005. Fire crews made further progress overnight in extinguishing a massive blaze at a fuel depot north of London, a fire service spokeswoman said on Tuesday. REUTERS/Stefan Rousseau/PA Pool 

One of the fuel storage tanks at the Buncefield oil depot in Hemel Hempstead, Hertfordshire, southeast England is hosed by firefighters as they continue to fight the blaze which has been raging for more than 48 hours, December 13, 2005, Fire crews made further progress overnight in extinguishing a massive blaze at a fuel depot north of London, a fire service spokeswoman said on Tuesday. REUTERS/Stefan Rousseau/PA/WPA Pool 

A destroyed building is seen as smoke billows from Buncefield fuel depot in Hemel Hempstead in southeast England December 12, 2005. Fire crews moved in to battle one of [Europe]'s biggest industrial blazes on Monday an inferno at a fuel depot north of London after being held back for 24 hours by heat and environmental worries. 

Smoke billows from the Buncefield fuel depot in Hemel Hempstead in southeast England December 12, 2005. Fire crews moved in to battle one of [Europe]'s biggest industrial blazes on Monday an inferno at a fuel depot north of London after being held back for 24 hours by heat and environmental worries. 

A destroyed building is seen as smoke billows from Buncefield fuel depot in Hemel Hempstead in southeast England December 12, 2005. Fire crews moved in to battle one of Europe's biggest industrial blazes on Monday an inferno at a fuel depot north of London after being held back for 24 hours by heat and environmental worries. REUTERS/Paul Hackett 

Smoke billows from the Buncefield fuel depot in Hemel Hempstead in southeast England December 12, 2005. Fire crews moved in to battle one of Europe's biggest industrial blazes on Monday an inferno at a fuel depot north of London after being held back for 24 hours by heat and environmental worries. REUTERS/Paul Hackett 

Smoke billows from the Buncefield fuel depot in Hemel Hempstead in southeast England December 12, 2005. Fire crews moved in to battle one of Europe's biggest industrial blazes on Monday an inferno at a fuel depot north of London after being held back for 24 hours by heat and environmental worries. REUTERS/Paul Hackett 

Smoke billows from the Buncefield fuel depot in Hemel Hempstead in southeast England December 12, 2005. Fire crews moved in to battle one of Europe's biggest industrial blazes on Monday an inferno at a fuel depot north of London after being held back for 24 hours by heat and environmental worries. REUTERS/Paul Hackett 

Debris lies on the ground as flames and smoke billow from an oil depot fire near Hemel Hempstead, southeast England December 12, 2005. Fire crews moved in to battle one of Europe's biggest industrial blazes on Monday an inferno at a fuel depot north of London after being held back for 24 hours by heat and environmental worries. REUTERS/Dylan Martinez 

Huge plumes of smoke billow from an oil depot fire in Hemel Hempstead, southeast England, December 11 2005. Explosions tore through a fuel depot north of London on Sunday, spewing out a huge tower of smoke and flame in what officials said could be the biggest incident of its kind in peacetime Europe. Police said there were 43 casualties but only one person appeared to have suffered serious injuries. REUTERS/Toby Melville Pictures of the Month December 2005 

Men watch plumes of smoke rise from an oil depot fire near Hemel Hempstead, southeast England, December 11, 2005. Explosions tore through a fuel depot north of London on Sunday, spewing out a huge tower of smoke and flame in what officials said could be the biggest incident of its kind in peacetime Europe. Police said there were 43 casualties but only one person appeared to have suffered serious injuries. REUTERS/Darren Staples 

Smoke is seen above central London December 11, 2005. Explosions tore through a fuel depot north of London before dawn on Sunday, creating a huge tower of smoke and flame and seriously injuring two people in what police said appeared to be an accident. REUTERS/Rob Dawson 

A general view shows smoke behind the British Telecom Tower in central London December 11, 2005. Explosions tore through a fuel depot north of London before dawn on Sunday, creating a huge tower of smoke and flame and seriously injuring two people in what police said appeared to be an accident. REUTERS/Rob Dawson 

Smoke billows after an explosion at a fuel depot in Hemel Hempstead in central England December 11, 2005. A series of explosions which tore through a fuel depot north of London before dawn on Sunday injured 36 people, four seriously, police said. REUTERS/Paul Hackett Pictures of the Month December 2005 Pictures of the Year 2005 

Smoke billows after an explosion at a fuel depot in Hemel Hempstead in central England December 11, 2005. A series of explosions and a massive fire erupted at the fuel depot north of London before dawn on Sunday and sent a large column of black smoke into the sky, witnesses said. REUTERS/Stephen Hird 

Policemen stand at a police cordon after an explosion at a fuel depot in Hemel Hempstead in central England December 11, 2005. A series of explosions and a massive fire erupted at the fuel depot north of London before dawn on Sunday and sent a large column of black smoke into the sky, witnesses said. REUTERS/Stephen Hird