Iran spars with U.S. and Britain over election

"It is a system which has been challenged and which now strikes back," said the diplomat, who asked not to be named.

"Obviously the regime is trying to preserve its position by very harsh repression. But that cannot hide the fact that this is a weakened regime. It has lost legitimacy both internally and externally," said Swedish Foreign Minister Carl Bildt, whose country takes over the EU presidency on Wednesday.

Official results showing Ahmadinejad won re-election by a landslide were greeted with disbelief by many Iranians, who agreed with complaints by Mousavi that the vote was rigged.

Mousavi has repeated demands for the election to be rerun, in defiance of Khamenei, who declared the poll fair, but his options for any further challenge appear to be dwindling.

The Guardian Council, Iran's top legislative body, is due to give its final verdict on the election and could rule on Monday.

The 12-man body has offered a partial recount -- rejected by Mousavi and fellow-candidate Mehdi Karoubi -- but it has already described the poll as the healthiest since the revolution.

Influential former president Akbar Hashemi Rafsanjani, seen by analysts as a possible mediator in any effort to defuse the election row, called for a thorough examination of complaints.

He praised a decision by Khamenei last week to extend a deadline for the Guardian Council to look into objections by defeated candidates, the ISNA news agency reported.

"I hope those who are involved in this issue thoroughly and fairly review and study the legal complaints," Rafsanjani said.

Breaking his post-election silence, he described events after the vote as a conspiracy by suspicious elements aimed at dividing people and the Islamic system, and also targeting people's trust in it.