IIn apparent defiance of Iran's supreme leader, a powerful cleric declared the Islamic Republic in crisis after a disputed election, and tens of thousands of protesters used Friday prayers to stage the biggest show of dissent for weeks.
Clashes erupted in central Tehran between police and followers of opposition leader Mirhossein Mousavi, who still contests official results that showed hardline president Mahmoud Ahmedinejad had been re-elected by a wide margin.
"Police fired teargas and beat supporters of Mousavi in Keshavarz Boulevard," a witness said, adding that protesters were carrying hundreds of green banners - Mr Mousavi's campaign colour - and chanting "Ahmadinejad, resign, resign".
State television showed footage of police firing tear gas to disperse protesters, chanting "Death to dictator" and "Mousavi we support you".
Some demonstrators shouted "Death to Russia" in protest at Moscow's declared recognition of Mr Ahmadinejad's election win.
Protest cries of Allahu Akbar [God is Greatest] were heard from Tehran rooftops again overnight and they were longer-lived than on previous evenings in the capital.
Former president Akbar Hashemi Rafsanjani, a moderate who backed Mousavi's election campaign, said many Iranians had doubts about the official result of the June 12th vote.
"I hope with this sermon we can pass through this period of hardships that can be called a crisis," said the influential cleric, leading prayers for the first time since the poll.
Live state radio broadcasts of Friday prayers at Tehran University, with a dual religious and political sermon delivered by a top cleric, have been a staple of revolutionary Iran.
Mr Rafsanjani did not go as far as Mr Mousavi and reformist candidate Mehdi Karoubi in denouncing the conduct of the vote, but his remarks still posed a clear challenge to Supreme Leader Ayatollah Ali Khamenei, who has upheld the election result and accused foreign powers of fomenting the unrest.
Mr Karoubi was physically beaten at the prayers, the state news agency IRNA quoted Tehran's governor Morteza Tamaddon as saying, blaming the beating on "the elements behind this suspicious event".
Some hardline clerics support Mr Ahmadinejad, but other senior Shi'ite prelates, including Grand Ayatollahs Yusof Saanei and Hossein Ali Montazeri, have criticised the authorities.
In the streets outside Tehran University, police used teargas and batons to disperse Mr Mousavi supporters who had flocked to the prayers. At least 15 people were arrested, a witness said.
Mr Mousavi, prime minister in the 1980s, attended the ceremony in his first official public appearance since the presidential vote, which he says was rigged. The authorities deny any fraud.
Mr Rafsanjani, who heads the Assembly of Experts - a powerful body that can in theory dismiss the supreme leader - attacked the way authorities had handled the poll and its aftermath.
"When people are not in the scene and their votes are not there, that government is not Islamic," he said, referring to opposition charges of vote-rigging. "Today is a bitter day."
Rafsanjani said it was vital to restore voters' faith in the system. "That trust cannot be brought back in a day or a night ... We have all been harmed," he added, calling for unity.
He criticised the Guardian Council, a clerical body which vets candidates and considers election complaints, for failing to do its job even though it was given five extra days to make its assessment. The council has denied any irregularities.
Using harsh language against the use of security forces to quell protests, Rafsanjani, who was a close aide to Iran's late revolutionary founder Ayatollah Ruhollah Khomeini, said:
"We knew what Imam Khomeini wanted. He didn't want the use of terror or arms, even in fights (for the revolution)."
The election stirred the most striking display of internal unrest in Iran, the world's fifth biggest oil exporter, since the 1979 revolution and exposed deep rifts in its ruling elite.
"If the Islamic and Republican sides of the revolution are not preserved, it means we have forgotten the principles of the revolution," said Mr Rafsanjani, who was enraged during the election campaign when Ahmadinejad accused him of corruption.
At least 20 people died in post-election violence. Mr Mousavi and the authorities blame each other for the bloodshed. Riot police and religious Basij militia eventually suppressed the street demonstrations, but Mr Mousavi has remained defiant.
Mr Rafsanjani also demanded the immediate release of people detained in the unrest and called for press curbs to be relaxed. Some of his own relatives, including his daughter Faezeh, were arrested briefly for joining pro-Mousavi rallies.
"It is not necessary for us to have a number of people in prisons ... we should allow them to return to their families," he said, in an emotional tone. "It is not necessary to pressure media. We should allow them to work freely within the law."
Mr Rafsanjani's robust stance appeared to set him on collision course with Khamenei, who has overtly backed Ahmadinejad in a departure from the supreme leader's accepted role as a lofty clerical arbiter above the political fray.
The election has further strained ties between Iran and the West, already at odds over Tehran's nuclear programme. Western powers criticised the crackdown. Iran accused them of meddling.
Reuters