Iranian riot police fired teargas in clashes with thousands of opposition supporters who shouted anti-government slogans during a Shi'ite mourning event yesterday, witnesses said.
The skirmishes broke out in north Tehran despite authorities having warned of a crackdown on attempts to use processions marking the solemn Ashura rituals to stage more protests against the government of President Mahmoud Ahmadinejad.
"Police told them they have five minutes to leave and, when they were still shouting slogans and persisted, policemen on motorbikes drove through the crowds and fired teargas," a witness said.
Rahesabz.net opposition website said security officials cancelled an Ashura speech by reformist ex-president Mohammad Khatami at Jamaran mosque, which was surrounded by police and security forces.
Ayatollah Ruhollah Khomeini, the late founder of the Islamic republic, used to address people at the same location.
Protesters shouted "death to this dictatorship" and "if Khomeini was alive, he would sure be with us", according to the witnesses.
Riot police and members of the Islamic Basij militia chased demonstrators into the nearby bustling Niavaran street and fired paintballs at them, witnesses said. Security forces were also seen arresting several protesters.
Reformist website Salaamnews also said "about 50 plainclothes forces broke into Jamaran" mosque and attacked people.
Opponents of Ahmadinejad's June 12 re-election have increasingly used a series of government-backed public events to mount protests, many of which have ended in clashes with police.
The 10-day Ashura ceremonies, which climax today, commemorate the death of Imam Hussein, a grandson of the Prophet Mohammed and one of the most revered figures of Shi'ite Islam.
The ceremonies are marked in Shi'ite majority countries such as Iran and Iraq by processions in which mainly young men flagellate their bare backs with chains.
At nightfall, streets appeared to be quiet in downtown Tehran as mourners went ahead with the traditional ceremonies of Ashura.
Rahesabz.net reported earlier clashes at several points along Enghelab street, a main thoroughfare where hundreds of thousands of opposition supporters had staged protest marches after Ahmadinejad's disputed re-election.
Security forces also chased protesters into a building housing the offices of the ISNA news agency, ISNA said, adding one of its reporters had been injured.
An elderly woman travelling on a city bus in the area was heard urging passengers to chant slogans such as "Ya Hossein, Mir Hossein" in support of opposition leader Mir Hossein Mousavi, a witness said.
Former premier Mousavi ran in the June election, which he charged was massively rigged in favour of Ahmadinejad to keep the hardliner in power.
Chants of "Ya Hossein" are common during Ashura when the faithful congregate in mosques or march in street processions beating their chest in mourning for the martyred Shi'ite imam.
The witness said passengers on the packed bus also chanted "Our Neda is not dead, it is the government which is dead," referring to protester Neda Agha Soltan, who bled to death during a June 20 protest in shocking scenes caught on video and viewed by millions around the world.