TEHRAN , Iran ( CNN ) -- One of Iran 's most powerful clerics , Ali Akbar Hashemi Rafsanjani , called Friday for the release of people arrested after last month 's disputed presidential election . Rafsanjani remains an influential figure in Supreme Leader Ayatollah Ali Khamenei 's circle . `` There is no need to have these numbers of people in prison , '' the former Iranian president said during his highly anticipated Friday sermon . `` Let them come back to their families . Let the enemy not laugh at us and criticize us . We must sympathize with those who have suffered damages . '' He warned : `` The system can not lose them . If the system reproaches them they will come back to us . '' Tens of thousands of people gathered in and around Tehran University as Rafsanjani spoke for about an hour , according to witnesses at the speech . Iranian police used tear gas to disperse some of the crowds . Many in the crowd chanted : `` Iranians are dying and the nation will not tolerate it . '' Traditionally , the speaker before the sermon asks those gathered to yell `` Death to America '' and `` Death to Israel . '' But on Friday , after being asked to curse those two countries , the crowd instead chanted , `` Allaho Akbar , '' meaning `` God is great '' -- the signature chant of the opposition movement . It was a key moment of defiance , as thousands in the crowd signaled that they were there to protest , not to support the regime . Later , as Rafsanjani was speaking , he mentioned China and Russia -- two nations that have said they recognize Iranian President Mahmoud Ahmadinejad as the winner of the election . Some in the crowd began chanting , `` Death to Russia '' and `` Death to China . '' Rafsanjani called on the people to stop , saying they should not call for death to anyone . Rafsanjani backs reformist Mir Hossein Moussavi , the opposition candidate who challenged Ahmadinejad in the June 12 election . Protesters say the election results were a sham , but the government stands by them . Watch more about Rafsanjani 's sermon » . Moussavi was at the sermon Friday . The semi-official Islamic Student News Agency posted a photo of him in attendance . A Facebook page associated with Moussavi also said he was at the sermon . The news agency 's photos also showed the two other opposition candidates from the election , Mehdi Karrubi and Mohsen Rezaie , at the sermon . There were reports , from people claiming to be witnesses , that Karrubi was attacked by members of the Basij , the paramilitary forces . CNN could not independently verify the reports because of the Iranian government 's restrictions on international journalists . After weeks of silence , Rafsanjani recently became increasingly vocal in opposing the brutal crackdown on demonstrators who protested election results . Earlier this month , the Iranian Labor News Agency quoted him as saying : `` People from across the county participated in the elections with excitement . But unfortunately , the events that occurred after that , and the difficulties created for some , left a bitter taste , and I do n't think any wakened consciousness would be satisfied with the resulting situation . '' Rafsanjani was under pressure Friday to deliver public support for the Iranian establishment . Lawmaker Mohammad Karim Shahrzad was recently quoted by the state-run Islamic Republic News Agency as saying : `` After a monthlong silence , the position of Hashemi Rafsanjani will be very important for those of all political inclinations , particularly those who are aiming at the ( destruction ) of the unity of the system . '' Shahrzad called on Rafsanjani -- head of the Assembly of Experts , the council responsible for appointing or removing the supreme leader -- to `` announce the support of the supreme leadership as the highest authority '' in his speech . A member of parliament said Rafsanjani 's sermon would be `` historic . '' Moussavi 's supporters took to the streets last month to protest the outcome of last month 's election that gave Ahmadinejad an overwhelming victory . Rafsanjani 's daughter , Faezeh , and four of his other relatives were detained briefly after taking part in one of those rallies . The widespread street protests and civil unrest led to the deaths of at least 20 demonstrators and the arrests of more than 1,000 , according to Iran 's state-run media . The numbers of casualties and arrests could not be independently verified by CNN because of restrictions on international journalists by the Iranian government . Rafsanjani remains an influential figure in Supreme Leader Ayatollah Ali Khamenei 's circle , but he has made `` a real break with the supreme leader in this case , '' Iranian-American author Hooman Majd told CNN recently . Rafsanjani was missing when Iran 's power brokers assembled on June 19 at Friday prayers to hear Khamenei declare Ahmadinejad the winner . Ahmadinejad is scheduled to be sworn in before parliament between August 2 and August 6 , according to Islamic Republic News Agency .
Rafsanjani calls for release of those held after June 12 vote . Rafsanjani : `` If the system reapproaches them they will come back to us '' Former president backs opposition leader Mir Hossein Moussavi . Police used tear gas to disperse crowds attending the sermon .