Akbar Hashemi Rafsanjani, one of Iran's most influential power-brokers, invigorated the country's embattled opposition yesterday by declaring that the disputed presidential election had broken the trust of the people and insisted that a debate was needed to end the "crisis" in his sermon at Tehran University. He also called for the immediate release of hundreds of people detained during huge pro-democracy demonstrations that were brutally crushed in the wake of the June 12 election. As the two-time former president spoke, baton-wielding police and basij militiamen fired tear gas and even paintball bullets to disperse tens of thousands of opposition supporters who were staging the biggest anti-government demonstration since July 9. At least 15 people were arrested, including a leading lawyer and women's rights campaigner, Shadi Sadr, who was bundled into a car and whisked away, according to reports. Mr Rafsanjani's sermon at Tehran University, the cradle of the 1979 Islamic Revolution, represented a robust challenge to the supreme leader, Ayatollah Ali Khamenei, although he did not mention him by name. The supreme leader had declared at the same highly symbolic venue a month ago that the election debate was over. Ayatollah Khamenei, attempting to portray a sense of calm normality in the country, had insisted there was no election fraud, that his hardline president was the rightful winner, and he ordered those challenging the vote to accept the outcome or face the consequences. Mr Rafsanjani cushioned his sermon with calls for unity in support of the Islamic Republic, but his challenge to the regime was unmistakable. "Today is a bitter day," he said. "I hope with this sermon we can pass through this period of hardships that can be called a crisis." It was the first time a senior establishment figure had characterised the post-election turmoil in such forthright terms. The system needed the people's support to enjoy legitimacy, Mr Rafsanjani said, arguing that the disputed election was endangering its republican aspect. "If the Islamic and republic aspects of the revolution are not preserved, it means we have forgotten the principles of the revolution." He added: "Our key issue is to return the trust which the people had and now to some extent is broken." Millions of Iranians feel disenfranchised by the "stolen" election which they believe was won by Mir Hossein Mousavi, a former prime minister whose candidacy was backed by Mr Rafsanjani. Mr Mousavi's attendance at yesterday's sermon was his first official public appearance in weeks. He has been under virtual house arrest, his every move watched by the security forces. Also present was another purportedly defeated reformist presidential candidate, Mehdi Karrubi, a cleric and former parliamentary speaker. His turban fell off when he was roughed up and abused by plain clothes militiamen as he entered the prayer hall, his son said. Outside the sprawling prayer hall, protesters, sporting green banners - the colour of Mr Mousavi's vibrant election campaign ? chanted slogans supporting the main opposition leader and calling on Mr Ahmadinejad to resign. Some also cried "death to the dictator," referring to Ayatollah Khamenei. Inside the more than usually crowded prayer hall, there were chants of "Mousavi, Mousavi, we support you". They died away when Mr Rafsanjani urged them "not to contaminate the position and the sanctuary of Friday prayers by comments and slogans". Astutely reminding worshippers on several occasions of his close relationship with the late Ayatollah Khomeini, founder of the 1979 Islamic Revolution, Mr Rafsanjani condemned the use of security forces to crush protests. "I speak as a person who has been with the revolution on a daily basis ? We knew what Imam Khomeini wanted. He didn't want the use of terror or arms, even in fights [for the revolution]," he said. Officially, Iran puts the death toll from the post-election upheaval at 20, although human rights activists believe hundreds may have been killed. Blinking back tears, Mr Rafsanjani called for the release of hundreds detained since the elections, among them many of Mr Mousavi's closest aides. "It is not necessary that in this situation people be jailed. Let them join their families. We should not allow enemies to rebuke and ridicule us because of detentions. We should tolerate each other," he said. This was another challenge to the regime which has branded the protesters "rioters" and stooges of hostile western powers. The regime had banned any public rallies which had largely died out since security forces launched an iron-fisted crackdown on the streets last month, but it could hardly tell people not to attend Friday prayers. Mr Rafsanjani's unexpectedly outspoken support will galvanise the opposition which are relying on him to help forge a new reformist political front to challenge the regime's hardline wing. @Email:mtheodoulou@thenational.ae