TEHRAN, Iran — The months-long confrontation between Iran's budding opposition movement and a hard-line government determined to stamp it out escalated sharply over the weekend, as parts of the capital became engulfed in fiery political protest and demonstrations broke out across the country on an important religious holiday.
Opposition Web sites reported 10 people were killed in Tehran and elsewhere on Sunday during Ashoura, a Shiite Muslim religious commemoration of the seventh-century martyrdom of Imam Hussein, a grandson of the prophet Muhammad. Officials put the death toll at five.
Among those said to have been killed by security forces or allied pro-government militias was Ali Habibi-Mousavi, described by Web sites as the 38-year-old nephew of opposition leader Mir Hossein Mousavi.
Despite a heavy crackdown, the protest movement that emerged from Iran's disputed June 12 presidential election has grown increasingly daring, with those demanding an abolition of Iran's Islamic system increasingly vocal, even as more religious and traditional social groups identify with the opposition.
The deaths now set the stage for more demonstrations coinciding with Habibi-Mousavi's burial today and the religiously significant third-, seventh- and 40th-day grieving ceremonies for him. Such cycles of protests linked to mourning ceremonies for slain protesters dislodged Shah Mohammad Reza Pahlavi more than three decades ago.
Police denied opening fire on demonstrators, accusing "mysterious" forces of being behind any violence. Iranian officials confirmed 300 arrests and five dead in the clashes, but several appeared to have died in accidents.
"According to reports, one person was killed with a bullet," said Brig. Gen. Ahmad Reza Radan, deputy commander of the Iran's police force, according to state media. "In light of the fact that the police did not use guns, this incident is very suspicious and is being investigated."
He added that "tens" of police were wounded in the unrest.
The government's official line was that the wave of antigovernment protests is a conspiracy hatched by Iranian exiles and foreign governments.
Reformist Web sites and witnesses also reported clashes and protests in the holy city of Qom, in the central Iranian cities of Esfahan, Shiraz, Arak, Najafabad and Kashan, in Babol in the north and Mashhad in the east.
The weekend's slogans were more radical, with protesters questioning not only the disputed June 12 re-election of President Mahmoud Ahmadinejad, who ran against the senior Mousavi and others, but shouting against Iran's supreme leader, Ayatollah Ali Khamenei.
And tactics became bolder, with demonstrators targeting police vehicles, setting vans and motorcycles on fire, and in one case burning down an office of the pro-government Basiji militia.
"Young boys, even younger than me, braved all the tear gas, and motorcycles of the antiriot police storming them," said Ehsan, a 22-year-old student who has attended all the protests. He asked that his full name not be used.
"Some of young people, only holding sticks ... counterattacked the anti-riot police and Basijis," he said. "As soon as they were beaten up or dispersed by tear gas they appeared on some other corners. I have never remembered such day with so many brave people."
Across the capital, witnesses described scenes of pandemonium, which were confirmed by video footage online. They were the most violent protests since June 20 clashes after the election.
One described Tehran as a war zone, and another likened the situation to open "civil war" as increasingly bold demonstrators took on security forces. In one case, protesters stripped a member of the security forces of his clothes before letting him go, a witness said.
Demonstrators continued their protests into the night, gathering in key Tehran squares after dark and clashing with security forces armed with tear gas and batons.
"There is no letup," said Farzad, a 30-year-old who attended Sunday's protests with his girlfriend. "We will go ahead until we topple the government."
Information from the New York Times was used in this report.