TEHRAN: Iran's electoral watchdog insisted on Friday the disputed presidential vote was the cleanest ever, as G8 leading powers urged Tehran to halt post-election violence but without questioning the result.

"After 10 days of examination, we did not see any major irregularities," Guardians Council spokesman Abbasali Kadkhodai told the state IRNA news agency, rejecting opposition allegations that have brought hundreds of thousands of demonstrators onto the streets.

"We have had no fraud in any presidential election and this one was the cleanest election we have had. I can say with certainty that there was no fraud in this election."

Two weeks after the vote, protests in Tehran over hardliner Mahmoud Ahmadinejad's re-election have receded after the authorities responded to the worst crisis since the 1979 Islamic revolution with a fierce crackdown that has intensified despite a chorus of international criticism.

State-run English-language Press TV said on Thursday that 20 people have been killed in the protests, including eight members of Iran's Basij militia. Other state media have reported that 17 civilians have been killed.

The Group of Eight leading powers at a meeting in Italy called on Iran to immediately put a halt to the post-election violence but refrained from calling into question the poll result.

Despite calls from Italy and France for a firm condemnation, the G8 foreign ministers backed off from harsh criticism and instead said the crisis should be settled "soon" through peaceful means.

"We want violence to stop immediately," Italian Foreign Minister Franco Frattini told a news conference after releasing a carefully-worded declaration from the world powers.

G8 member Russia had warned against isolating Iran with a toughly-worded condemnation, arguing that it could trigger a backlash from Tehran that would jeopardise cooperation with the Islamic republic over its nuclear programme.

"We are concerned about the aftermath of the Iranian presidential election," the foreign ministers from Britain, Canada, France, Germany, Italy, Japan, Russia and the United States said in their statement.

"We fully respect the sovereignty of Iran. At the same time we deplore post-election violence which led to the loss of lives of Iranian civilians and urge Iran to respect fundamental human rights."

But in a nationally broadcast sermon at the main weekly Muslim prayers in Tehran, hardline cleric Ahmad Khatami called on the government to impose even tighter controls on the foreign media.

"How can they be allowed to wander round the country with their satellite phones giving information that provokes people to take to the streets," he asked.

Khatami suggested that any demonstrator who resorted to violence during the protests should face the death penalty. "Anyone who takes up arms against the people is a mohareb and Islam has prescribed the toughest punishment for such offenders," he said.

US senators bluntly charged on Thursday that the June 12 election was rigged and vowed to help the opposition defeat curbs on news and the social networking Internet sites it has used to organise demonstrations.

But since an address to the nation last week by supreme leader Ayatollah Ali Khamenei in which he warned that the defeated candidates would be held responsible for any "blood, violence and chaos" on the streets of Tehran, the protests have nearly stopped.

On Wednesday, an attempt by a few hundred demonstrators to gather near parliament was quashed by police and militiamen, witnesses told AFP.

Despite the restrictions on the foreign media, images of police brutality have still spread worldwide via amateur video over the Internet.

One clip in particular of the fatal shooting of young woman demonstrator Neda Agah-Soltan has come to symbolise the regime's iron-fisted response to the protests.

Arash Hejazi, a doctor who tried to save her, told the BBC the shooter was identified by the crowd as a Basij militiaman.

Although the street protests have died down, Iran's rulers are still facing a major crisis, with cracks emerging within the regime itself.

On Friday defeated conservative candidate Mohsen Rezai charged that the events of the past fortnight had damaged the authority of the Islamic regime.

"More important than the elections, people's lives and property and the credibility of the Islamic republic have been damaged in recent weeks and we must act to stop that," said Rezai, a former commander of the elite Revolutionary Guards.