Iran reform leader calls for rally

A crackdown on dissent continued, with more arrests of opposition figures reported.

The country's most powerful military force - the Revolutionary Guard - said that Iranian websites and bloggers must remove any materials that "create tension" or face legal action.

Supreme Leader Ayatollah Ali Khamenei has told Mr Mousavi to pursue his demands through the electoral system and called for Iranians to unite behind their Islamic government, an extraordinary appeal in response to tensions over the presidential vote.

But Mr Mousavi appears unwilling to back down, issuing on his website a call for a mass demonstration on Thursday.

"We want a peaceful rally to protest the unhealthy trend of the election and realise our goal of annulling the results," said Mr Mousavi.

He called for "a new presidential election that will not repeat the shameful fraud from the previous election".

Mousavi and his supporters accuse the government of rigging the June 12 election to declare hard-line President Mahmoud Ahmadinejad the overwhelming winner.

Their street protests, paired with dissent from powerful clerical and political figures, have presented one of the gravest threats to Iran's complex blend of democracy and religious authority since the system emerged from the 1979 Islamic Revolution.

Blogs and websites such as Facebook and Twitter have been vital conduits for Iranians to inform the world about protests and violence.