A supporter of former presidential candidate Mirhossein Mousavi flashes victory sign while holding a campaign poster during a rally in Tehran, June 15, 2009. REUTERS/Morteza Nikoubazl (IRAN POLITICS ELECTIONS) 

Demonstrators hold posters as they head towards Azadi (freedom) square during a rally in support of defeated presidential candidate Mirhossein Mousavi in western Tehran June 15, 2009. REUTERS/Caren Firouz (IRAN POLITICS ELECTIONS) 

A demonstrator heads towards Azadi (freedom) square during a rally in support of defeated presidential candidate Mirhossein Mousavi in western Tehran June 15, 2009. REUTERS/Caren Firouz (IRAN POLITICS ELECTIONS) 

A man holds up a placard during a rally in support of defeated presidential candidate Mirhossein Mousavi in Tehran June 15, 2009. REUTERS/Morteza Nikoubazl (IRAN) 

A supporter of former presidential candidate Mirhossein Mousavi holds a placard upside down while attending a rally in Tehran, June 15, 2009. REUTERS/Morteza Nikoubazl (IRAN POLITICS ELECTIONS CONFLICT) 

A supporter of defeated presidential candidate Mirhossein Mousavi holds up a photograph of him while attending a rally in Tehran June 15, 2009. REUTERS/Morteza Nikoubazl (IRAN POLITICS ELECTIONS) 

A demonstrator shouts slogans during a rally in support of former Presidential candidate Mirhossein Mousavi western Tehran June 15, 2009. REUTERS/Caren Firouz (IRAN POLITICS ELECTIONS) 

A supporter of former presidential candidate Mirhossein Mousavi holds a placard reading: "Ahmadinejad went" during a rally in Tehran June 15, 2009. REUTERS/Morteza Nikoubazl (IRAN POLITICS ELECTIONS) 

Demonstrators head towards Azadi (freedom) square during a rally in support of defeated presidential candidate Mirhossein Mousavi in western Tehran June 15, 2009. REUTERS/Caren Firouz (IRAN POLITICS ELECTIONS) 

A demonstrator shows a picture of former presidential candidate Mirhossein Mousavi during a rally in support of Mousavi near the Azadi (Freedom) monument, western Tehran June 15, 2009. REUTERS/Caren Firouz (IRAN POLITICS ELECTIONS IMAGES OF THE DAY) 

Demonstrators head towards Azadi (freedom) square during a rally in support of defeated presidential candidate Mirhossein Mousavi in western Tehran June 15, 2009. REUTERS/Caren Firouz (IRAN POLITICS ELECTIONS CONFLICT) 

Demonstrators head towards Azadi (freedom) square during a rally in support of defeated presidential candidate Mirhossein Mousavi in western Tehran June 15, 2009. REUTERS/Caren Firouz (IRAN POLITICS ELECTIONS) 

A supporter of defeated presidential candidate Mirhossein Mousavi flashes the victory sign as he holds a campaign poster during a rally in Tehran June 15, 2009. REUTERS/Morteza Nikoubazl (IRAN POLITICS ELECTIONS) 

Two women stand at a mosque as they watch the supporters of former presidential candidate Mirhossein Mousavi (not pictured) during a rally in Tehran, June 15, 2009. REUTERS/Morteza Nikoubazl (IRAN POLITICS ELECTIONS RELIGION) 

A supporter of defeated presidential candidate Mirhossein Mousavi holds a placard during a rally in western Tehran June 15, 2009. REUTERS/Caren Firouz (IRAN POLITICS ELECTIONS CONFLICT) 

Men hold campaign posters as they sit atop a tree during a rally in support of defeated presidential candidate Mirhossein Mousavi in Tehran June 15, 2009. REUTERS/Morteza Nikoubazl (IRAN POLITICS ELECTIONS) 

Supporters of defeated presidential candidate Mirhossein Mousavi hold campaign posters and a placard that read: "We are not leftovers. Our vote determines." during a rally in Tehran June 15, 2009. REUTERS/Morteza Nikoubazl (IRAN POLITICS ELECTIONS) 

Supporters of defeated presidential candidate Mirhossein Mousavi flash victory signs as one of them holds his picture during a rally in support of Mousavi, in Tehran June 15, 2009. REUTERS/Raheb Homavandi (IRAN POLITICS ELECTIONS) 

A supporter of defeated presidential candidate Mirhossein Mousavi holds his photograph in front of Azadi (freedom) square during a rally in western Tehran June 15, 2009. REUTERS/Caren Firouz (IRAN POLITICS ELECTIONS) 

A supporter of defeated presidential candidate Mirhossein Mousavi flashes victory signs as he shouts slogans during a rally in Tehran June 15, 2009. REUTERS/Morteza Nikoubazl (IRAN POLITICS ELECTIONS) 

A demonstrator points towards a police helicopter during a rally in support of former Presidential candidate Mirhossein Mousavi western Tehran June 15, 2009. REUTERS/Caren Firouz (IRAN POLITICS ELECTIONS) 

Demonstrators gesture and show photographs of defeated presidential candidate Mirhossein Mousavi during a rally in support of Mousavi in western Tehran June 15, 2009. REUTERS/Caren Firouz (IRAN POLITICS ELECTIONS) 

A supporter of former presidential candidate Mirhossein Mousavi holds a campaign poster and a piece of green cloth during a rally in Tehran, June 15, 2009. Green is the symbolic colour of Mousavi's campaign. REUTERS/Morteza Nikoubazl (IRAN) 

A supporter of former presidential candidate Mirhossein Mousavi wears a head band reading: "Mirhossein Mousavi", as she hides her face with green clothes, during a rally in Tehran, June 15, 2009. Green is the symbolic colour of Mousavi's campaign. REUTERS/Morteza Nikoubazl (IRAN POLITICS ELECTIONS CONFLICT) 

Supporters of defeated presidential candidate Mirhossein Mousavi flash victory signs during a rally in support of Mousavi, in Tehran June 15, 2009. REUTERS/Raheb Homavandi (IRAN POLITICS ELECTIONS) 

Supporters of defeated presidential candidate Mirhossein Mousavi flash victory signs as one of them holds his picture during a rally in support of Mousavi, in Tehran June 15, 2009. REUTERS/Raheb Homavandi (IRAN POLITICS ELECTIONS) 

Riot police and members of Iran's Basij militia watch supporters of defeated presidential candidate Mirhossein Mousavi as they pass a Basij base during a rally in western Tehran June 15, 2009. REUTERS/Caren Firouz (IRAN POLITICS ELECTIONS) 

Supporters of defeated presidential candidate Mirhossein Mousavi flash victory signs as one of them holds his photograph during a rally to support of Mousavi in Tehran June 15, 2009. REUTERS/Raheb Homavandi (IRAN POLITICS ELECTIONS) 

Supporters of former presidential candidate Mirhossein Mousavi attend a rally in Tehran, June 15, 2009. REUTERS/Morteza Nikoubazl (IRAN POLITICS ELECTIONS) 

A man climbs a monument in Azadi (freedom) square during a rally in support of former presidential candidate Mirhossein Mousavi in Tehran June 15, 2009. The Persian script reads: "Death to dictator". REUTERS/Morteza Nikoubazl (IRAN POLITICS ELECTIONS) 

A supporter of defeated presidential candidate Mirhossein Mousavi flashes a victory sign during a rally in support of Mousavi, in Tehran June 15, 2009. The placard reads: "Silence". REUTERS/Raheb Homavandi (IRAN POLITICS ELECTIONS) 

A cleric sits in Azadi (freedom) square while attending a rally in support of former presidential candidate Mirhossein Mousavi in Tehran, June 15, 2009. REUTERS/Morteza Nikoubazl (IRAN POLITICS ELECTIONS) 

A demonstrator gestures towards a police helicopter during a rally in support of defeated presidential candidate Mirhossein Mousavi western Tehran June 15, 2009. REUTERS/Caren Firouz (IRAN POLITICS ELECTIONS)