Iran's Supreme Leader Ayatollah Ali Khamenei declared today that a disputed election result would stand, despite street protests that Iranian officials say Britain and the United States have incited.
The opposition refused to be bowed. Reformist cleric Mehdi Karoubi, who came last in the June 12th presidential election, called the new government "illegitimate" and around 200 protesters braved the security crackdown near parliament.
Riot police later used teargas to break up the protest.
Police and militia have largely succeeded in taking back control of the streets this week after the biggest anti-government protests since the 1979 Islamic revolution. The hardline leadership is refusing to give ground.
"I had insisted and will insist on implementing the law on the election issue," said Mr Khamenei, the most powerful figure in Iran. "Neither the establishment nor the nation will yield to pressure at any cost."
Iran is blaming the discontent on foreign powers.
"Britain, America and the Zionist regime (Israel) were behind the recent unrest in Tehran," Interior Minister Sadeq Mahsouli said, according to the semi-official Fars news agency.
Foreign Minister Manouchehr Mottaki said Iran was weighing whether to downgrade ties with Britain after each country expelled two diplomats this week. He also announced he had "no plans" to attend a G8 meeting in Italy this week on Afghanistan.
His remarks, a day after US President Barack Obama said he was "appalled and outraged" by the clampdown in Iran, provided more evidence of rising tension with the West.
Mr Obama called Iran's accusations that Washington was stoking unrest "patently false and absurd". Britain also denies the charge.
Security forces have clamped a tight grip on Tehran to prevent more rallies against the June 12th poll, which reformists say was rigged to return President Mahmoud Ahmadinejad to power and keep out moderate former Prime Minister Mirhossein Mousavi.
The furore over the election has exposed deep rifts within Iran's political elite, with Mr Khamenei solidly backing Mr Ahmadinejad against Mr Mousavi, who has the support of former presidents Akbar Hashemi Rafsanjani and Mohammad Khatami.
Many of Iran's senior Shia clerics in the holy city of Qom have stayed out of the political fray, although Grand Ayatollah Hossein Ali Montazeri has called for three days of national mourning from today for those killed in the protests.
Up to 20 people have been killed in the protests, according to Iran's state English-language Press TV. Amateur footage of clashes with security men, and of some of the deaths, has been posted on the Internet and viewed around the world.
Reuters