Tehran: Iranian state television said on Monday that more than 15 people were killed in riots which rocked Tehran, of whom more than 10 were members of "anti-revolutionary terrorist" groups.
The other five who died during Sunday`s fierce clashes in the Iranian capital were killed by "terrorist groups," the report said, without elaborating.
"In a suspicious act, five people were killed by terrorist groups and the ministry of intelligence announced that more than 10 of the known members of anti-revolutionary terrorist groups were killed," the state television website said.
Iranian reformist websites said on Sunday that security forces killed a nephew of opposition leader Mir Hossein Mousavi while police confirmed that five people died during the massive anti-government rallies in Tehran.
Leading Iran cleric condemns Ashura deaths
An opposition leader criticized Iran`s hardline rulers on Monday for killing innocent people during a religious festival, a reformist website reported.
Police said five people died in Tehran when pro-reform protesters fought security forces on Sunday, the most violent clashes since a contested June 12 presidential vote sparked political turmoil across Iran.
"What has happened to this religious system that it orders the killing of innocent people during the holy day of Ashura?," moderate cleric Mehdi Karoubi, who came fourth in the election, said in a statement, the Jaras website reported.
"Why is such a holy day not respected by the rulers?"
Opposition websites said police opened fire on protesters in central Tehran. Eight people were killed in the capital and other Iranian cities when tens of thousands of opposition backers took to the streets, they said.
The deaths were the first in street protests since the immediate aftermath of the disputed June election.
Among the dead was opposition leader Mirhossein Mousavi`s nephew, whose death was described as a "martyrdom" by a Mousavi ally. State TV said "unknown assailants" killed Ali Habibi Mousavi Khamene.
Police said investigations were under way into the suspicious deaths and more than 300 protesters had been arrested in Tehran.
Jaras said police shot and killed four protesters in central Tehran and that unrest had spread to other parts of Iran, including the holy city of Qom, Shiraz, Isfahan, Najafabad, Mashhad and Babol.
The reports could not be independently verified because foreign media are banned from covering protests.
The White House condemned the "unjust suppression" of civilians by the Iranian government and said the United States was on the side of protesters.
Unrest across Iran
The killings showed that the confrontation between the opposition and the clerical establishment had entered a volatile phase, in which the security forces appeared determined to stamp out the pro-reform movement.
The disputed re-election of hardline President Mahmoud Ahmadinejad has plunged Iran into its biggest internal crisis since the 1979 Islamic revolution, exposing deepening divisions in its ruling elite and setting off a wave of protests that the opposition says left over 70 people dead.
Officials say the death toll was half that number.
The post-election turmoil has also made Iranian officials unable to resolve a dispute over Iran`s nuclear program, which the West fears is a cover to build bombs. Iran denies this.
Authorities had strongly warned the opposition to avoid using the two-day Shi`ite Muslim Tasoua and Ashura festival over the weekend to revive protests against the clerical establishment.