By Jay Deshmukh

TEHRAN - Iranian authorities arrested at least 457 people after violent post-election clashes that left 10 people dead, state radio reported, as the nation's clerical leaders battled to contain the worst crisis since the Islamic revolution.

Opposition leader Mir Hossein Mousavi, who has led a wave of massive protests over what he says was a rigged presidential election, remained defiant as he urged supporters to continue demonstrating but to adopt "self-restraint."

Iranian state radio, quoting the police, said the mass arrests were made when demonstrators and security forces clashed on Saturday around the capital's Azadi square in violence that left 10 people dead.

The streets of Tehran were tense on Monday but have remained largely quiet since Sunday and there were no immediate reports of any planned demonstrations. Witnesses said they did not see many security personnel out on the streets.

Mousavi, a post-revolution prime minister who lost to Mahmoud Ahmadinejad by a landslide according to official results from the June 12 election, told his supporters to continue their protests.

"The revolution is your legacy. To protest against lies and fraud is your right. Be hopeful that you will get your right and do not allow others who want to provoke your anger... to prevail," he said on his newspaper website Kalemeh.

But he urged his supporters -- who have adopted his green campaign colour -- to refrain from violence and show self-restraint. "The nation belongs to you," he said on a statement.

The foreign media has been barred from covering the demonstrations as part of tight new restrictions on their work since the upheaval began.

A total of 17 people have been killed and many more wounded, according to state media, while hundreds of protestors as well as prominent reformists, journalist and analysts have been rounded up in the post-election turmoil.

World leaders have voiced mounting alarm over the unrest, which has jolted the pillars of the Islamic regime and raised concerns over the future of the Shiite Muslim powerhouse, the fourth largest oil producer in the world.

Iranian leaders have lashed out at "meddling" by Western nations, and taken the foreign media and the exiled opposition to task.

The Guardians Council, the electoral watchdog has said it was ready to conduct a random recount of 10 percent of votes.

Independent British think tank Chatham House said the election results show "irregularities" in the turnout and "highly implausible" swings to Ahmadinejad, according to an analysis published on Sunday.

There would have to have been a radical shift in rural voting patterns and a "highly unlikely" change of heart among former reformist voters for Ahmadinejad to win as he did, the study concluded.

Ahmadinejad, who had put Iran on a collision course with the West during his first four-year term with his anti-Israeli tirades and defiant stance on the country's nuclear drive, was declared the victor with 63 percent of the vote.

On Sunday, he bluntly told the United States and Britain to stop interfering while Foreign Minister Manouchehr Mottaki accused London of plotting for the past two years to sabotage the election.

"By making hasty comments, you will not have a place in the circle of the Iranian nation's friends. Therefore, I recommend you to correct your interfering positions," Ahmadinejad said.

In his latest comments on Saturday, US President Barack Obama, who has appealed for dialogue with Tehran after three decades of severed ties, urged Iran to stop "all violent and unjust actions".

Dianne Feinstein, who chairs the Senate Intelligence Committee, said: "It is very crucial, as I see it, that we not have our fingerprints on this. That this really be truly inspired by the Iranian people."

"We don't know where this goes. And I sure wouldn't want to be responsible for thousands of people being killed, which is a distinct possibility."

British Foreign Secretary David Miliband rejected the charges that protesters were being "manipulated or motivated" by foreign countries and denounced what he said were Iran's effort to turn the election dispute into a "battle" with the outside world.

French Foreign Minister Bernard Kouchner condemned what he called "this brutal repression" while President Nicolas Sarkozy told Qatar's QNA news agency that the attitude of the Iranian authorities was "inexcusable".

Iranian authorities have cracked down on the foreign media.

Canadian journalist Maziar Bahari who was working for Newsweek was detained without charge and not been heard of since, the magazine said.

The BBC's permanent correspondent in Tehran has been ordered to leave within 24 hours and the authorities warned the British media of further action if the "interference" continues.

Dubai-based television channel Al-Arabiya said its Tehran bureau had been ordered to remain closed indefinitely for "unfair reporting" of the election.

Mousavi on Saturday fired off an unprecedented criticism of supreme leader Ayatollah Ali Khamenei after police clashed with thousands of protesters who defied an ultimatum from Khamenei for an end to their street rallies.

Khameini on Friday ruled out any election fraud and warned that opposition leaders would be responsible for "blood, violence and chaos" if there was no end to protests.