Hundreds of thousands of government supporters rallied across Iran on Wednesday, swearing allegiance to the clerical establishment and accusing opposition leaders of causing unrest in the Islamic state.

Iran's police chief warned supporters of opposition leader Mirhossein Mousavi to expect harsh treatment if they joined illegal anti-government rallies, three days after eight protesters were killed in demonstrations.

Hundreds of thousands took part in the government-organised demonstrations, which state television broadcast live, chanting slogans against the opposition leaders -- Mousavi and moderate defeated presidential candidate Mehdi Karoubi.

"You should repent ... otherwise the system will confront you as a 'mohareb' (enemy of God)," cleric Ahmad Alamolhoda told a Tehran rally, directing his remarks at reformist leaders, state TV reported. Under Iran's sharia (Islamic law) the sentence for a mohareb is death.

Iran's state news agency IRNA said that two leaders of "sedition" had fled to a northern Iranian province.

"Two of those who played a major role in igniting tension in Iran following the vote, fled Tehran and went to a northern province because they were scared of people, who demanded their punishment," IRNA reported, without naming the two.

The report was immediately denied by a son of Karoubi.

"My father and Mousavi are in Tehran and IRNA's report is baseless. They are still pursuing the people's demands," Hossein Karoubi told moderate Parlemannews.

In Tehran, crowds burned American and British flags, condemning what they said was interference by Washington and London in Iran's internal affairs.

Semi-official Fars news agency said a group of hardliners gathered in front of the British embassy in Tehran, chanting "the British embassy should be closed down".

Iran's top authority accused the West of basing its actions towards Iran on "distorted realities".

"They are under influence of foreign and Zionist news agencies' reports," Iran's Supreme Leader Ayatollah Ali Khamenei said, the students news agency ISNA reported.

There was no word of any opposition supporters on the streets on Wednesday, despite talk of demonstrations on reformist websites. Foreign media are restricted from moving around to report on such protests, which are illegal.

In Iran's bloodiest unrest since the immediate aftermath of the disputed June 12 presidential election, eight people were killed on Sunday and at least 20 pro-reform figures, including three senior advisers to Mousavi, were arrested.

"Punish opposition leaders"

UN Human Rights chief Navi Pillay called on the Tehran government on Wednesday to curb excess use of force by its security services and expressed shock at the violence.

The US and its European allies have condemned Iran over Sunday's clashes.

Television footage of Wednesday's rallies in various cities showed people chanting.

"Mousavi is responsible for bloodshed ... We support our Supreme Leader". Some of them carried pictures of Khamenei. Similar rallies took place on Tuesday.

"People want the leaders of sedition to be punished. We will not remain silent over insulting the religion," one speaker told a Tehran rally, state TV reported.

"We have asked the judiciary to arrest the leaders of this sedition," said hardline MP Hasan Norouzi, without saying how many lawmakers made the demand. "Karoubi, Mousavi and all those who ignite tension should be arrested and tried."

Fars news agency said Mousavi's nephew, who was killed in Sunday's bloodshed, was buried on Wednesday at Tehran's Behesht-e Zahra cemetery.

Concern over political unrest in Iran helped to push oil prices briefly above $79 a barrel to fresh five-week highs on Tuesday and they held near that level on Wednesday.

Iran's police chief said "there was no more room for tolerance over participants in illegal rallies".

"Those who participate in illegal rallies will be confronted more harshly and the judiciary will confront them more decisively," said Esmail Ahmadi-Moqadam, the IRNA news agency reported. "Some of Sunday's protesters are ... considered as mohareb and will be confronted firmly."

Pro-government demonstrators also chanted "Death to America" and "Death to Britain", state TV reported. Iran, locked in a row with the West over its nuclear programme, has accused foreign powers of meddling in its affairs, provoking robust denials. – Reuters