By NAZILA FATHI
The demonstrators, who defied an official ban and turned a Shiite mourning ceremony into a protest, underlined the government’s inability to suppress the opposition despite the use of violence. Protests have continued since a disputed presidential election in June, and one of the largest was expected on Sunday.
Witnesses and an opposition Web site reported that the police and Basij militia forces beat and arrested protesters in central Tehran.
The police fired tear gas at protesters in three central squares — Imam Hussein, Enghelab and Ferdowsi — the opposition Web site Jaras reported. The militia forces attacked protesters with batons and chains, the Web site said. Government forces also attacked cars whose drivers had honked in support of the protesters, and smashed their windows. Many vehicles’ license plates were taken away.
“They beat up people relentlessly although many were in mourning groups for Imam Hussein,” said a witness, who spoke on condition of anonymity. “I saw many people with bloody noses or limping away. It was clear that they particularly targeted women and savagely beat them.”
The clashes came on the Shiite holiday of Tasooa, a day before Ashura, the anniversary of the day Imam Hussein, a grandson of the Prophet Muhammad, was killed in battle.
The chief of the national police, Ismail Ahmadi Moghadam, said Saturday that security forces would use “minimum violence” against protesters, the semiofficial ISNA news agency reported. He said, “We will confront them forcefully, which means we will identify the leaders and will arrest them.”
In the evening, about 50 vigilantes armed with chains, batons and pepper spray disrupted a speech by Mr. Khatami at Jamaran Mosque in Tehran, the home mosque of Ayatollah Ruhollah Khomeini, the spiritual leader of Iran’s Islamic revolution.
Thousands of opposition supporters converged on the neighborhood, witnesses said, and government forces fired tear gas and threatened to shoot if the protesters did not leave.
“As the number of protesters increased, the government forces quickly brought in more forces and waged a very savage attack on people,” a witness said. “I saw a 23-year-old woman stabbed.”
Late Saturday night, the mosque was still surrounded by riot police and Basij militia forces, and it was not clear if Mr. Khatami was still inside.
The mosque sits next door to the house of Ayatollah Khomeini, many of whose relatives have sided with the opposition in this conflict. This year for the first time the government canceled the Shiite mourning ceremonies at Ayatollah Khomeini’s shrine, which were to have taken place in conjunction with the holidays on Saturday and Sunday.
Government forces also raided the building of the ISNA student news agency, where some of the protesters had sought shelter, Jaras reported. Reuters reported that an ISNA employee’s skull was fractured.
A video posted on an opposition Web site showed protesters on a public bus on Saturday chanting, “This is the month of blood, Yazid will fall.” The chant was a reference to the villain in Shiite Islam, Yazid, the caliph who killed Imam Hussein in a battle in 680. Some protesters have been referring to the Iranian authorities as Yazid.
The police took the extraordinary measure of searching people’s bags in subway stations leading to downtown Tehran to confiscate anything green, the color representing the opposition. They also checked residents’ cellphones and confiscated those with images from the protests, Jaras reported.
Opposition supporters have been posting cellphone videos of protests on opposition Web sites.
The government also jammed satellite television channels beamed into Iran, and Internet speed was excruciatingly slow, a Tehran resident said.
Protesters vowed to show up on Sunday in larger numbers. Large protests for Ashura had been planned for weeks, but the day will also coincide with the traditional seventh day of mourning for a senior cleric, Ayatollah Hossein Ali Montazeri, who died last week.
The government has banned mourning ceremonies for Ayatollah Montazeri, who became a revered figure for the opposition for his outspoken criticism of the government.
The opposition Norouz Web site also reported that there would be a protest by families of former senior officials who had been detained since the disputed election in June.
