Iran's supreme leader, Ayatollah Ali Khamenei, remained defiant today in the face of vote-rigging allegations as he condemned the protests that have rocked the country since last week's disputed elections.

The reformist presidential challenger, Mir Hossein Mousavi, was conspicuous by his absence from Friday prayers at Tehran University, where Khamenei was making his first public appearance since controversially endorsing Mahmoud Ahmadinejad's election as president.

Some followers of Mousavi, who support his claim to have won the election, had called for a boycott of prayers at the university because of the refusal to annul the result of the poll, but TV pictures showed thousands of people listening to Khamenei and occasionally chanting affirmation of his words.

He described the 85% turnout at the election as a "great accomplishment" and a "political earthquake" for Iran's enemies. The supreme leader said he was bringing a message for "leaders of world arrogance, the western countries".