Witnesses say police use sticks, batons and belts on people who gathered to commemorate dead.
Iranian riot police beat mourners who staged a defiant gathering at a cemetery on Thursday to commemorate protesters killed in post-election violence last month, witnesses said.Police used sticks, batons and belts on some of the hundreds of people who turned up at the cemetery south of Tehran where the protesters are buried and also forced opposition leader Mirhossein Mousavi to leave, witnesses said.
The graveyard became a flashpoint as crowds gathered to mark the 40th day since the death of Neda Agha-Soltan, a young woman who came to symbolise the protest movement against the re-election of President Mahmoud Ahmadinejad.
Witnesses said about 150 police and some members of the Islamic Basij militia were in and around Behesht-e Zahra cemetery, with a number surrounding the graveyard where Neda is buried.
Witnesses said Mousavi managed to get out of his car and walk up to Neda's grave.
"Mousavi was however not allowed to recite the Koran verses said on such occasions and he was immediately surrounded by anti-riot police who led him to his car," a witness said as people chanted "Ya Hossein! Mirhossein!".
"At the same time mourners also surrounded his car and were not allowing him to go. The police then started pushing the mourners after which Mousavi drove off."
Mousavi and Mehdi Karroubi, who have waged a defiant protest campaign since losing to Ahmadinejad in what they brand a rigged election, had announced they would go to the cemetery after the authorities banned another memorial ceremony.
A graphic Internet video of Neda bleeding to death on a Tehran street on June 20 was seen around the world and triggered an outcry over the Iranian crackdown on demonstrators.
Witnesses said police had blocked three streets leading to the graveyard where Neda is buried.
About 40 people, wearing green wristbands and T-shirts – the signature colour of Mousavi's election campaign – were earlier seen standing around Neda's grave which was decorated with candles and flowers.
Mousavi, a prime minister in the post-revolution years who was Ahmadinejad's main challenger, has consistently refused to acknowledge his rival's victory, saying it was a "shameful fraud."
Hundreds of thousands of people poured on to the streets of Tehran after the election result and in the ensuing violence about 30 people were killed, scores wounded and several thousand arrested, Iranian officials say.
Karroubi's deputy Rasool Montajebnia suggested that Mousavi, former parliament speaker Karroubi and reformist former president Mohammad Khatami form a joint council to advance the opposition movement.
"If they individually carry out actions, it cannot become a comprehensive movement and address people's demands," he was quoted as saying by Karroubi's reformist newspaper Etemad Melli.
"There is no way but to establish a council of reform... around the axis of Khatami, Karroubi and Mousavi."
The election tumult has driven deep rifts between the nation's ruling elite and clerical groups, and Ahmadinejad has since come under fire even from his own hardline supporters over a series of controversial political decisions.
In recent days, the authorities have made gestures towards the opposition, including releasing about 140 protesters and promising to free by Friday more of the some 250 still behind bars.
But Khatami said just releasing the protesters was not enough.
"Blood has been spilled and several families are damaged psychologically. Illegal and un-Islamic acts have been committed against the people... crimes have been committed. Lives have been lost," he said on his Baran foundation website.
US Secretary of State Hillary Clinton on Wednesday said it was "imperative" for Iran to release political prisoners, adding that their detention showed "the political situation inside of Iran has not yet resolved itself."
Twenty people accused of rioting are to go on trial from Saturday on charges including attacks on government and military offices, arson, vandalism and contact with "enemies" including exiled opposition group the People's Mujahedeen.
"We have pictures showing them committing these crimes," Tehran prosecutor Saeed Mortazavi said on Wednesday.
Iran's police chief Esmail Ahmadi Moghaddam was quoted by the Mehr news agency on Wednesday as acknowledging possible abuse by the security forces during the post-election troubles.
Ahmadinejad is due to be sworn in next week but is facing harsh criticism from powerful conservatives who have warned him to obey supreme leader Ayatollah Ali Khamenei or face the consequences.