TEHRAN – Iran's hardline Revolutionary Guards on Monday threatened to crack down on street protests after opposition leader Mirhossein Mousavi called on supporters to stage more demonstrations over the disputed June 12 election.

In the current sensitive situation ... the Guards will firmly confront in a revolutionary way rioters and those who violate the law, said a statement published on the Guards' website.

The statement by the Guards, who are viewed as the most loyal guardian of the ruling clerical establishment, clearly signaled a crackdown on any fresh unrest over the re-election of hardline President Mahmoud Ahmadinejad.

Mousavi, who was officially beaten into second place by Ahmadinejad in an election which he says was rigged, called late on Sunday for fresh protests by his supporters.

Protesting against lies and fraud (in the election) is your right, Mousavi said in a statement on his website.

At the same time, Mousavi made a veiled appeal to the security forces to show restraint in handling demonstrations -- a move likely to be viewed with deep suspicion by a conservative leadership that has vowed to use force wherever necessary to quell opposition.

Ramming the point home, the Revolutionary Guards said they would not hesitate to confront illegal protests organized by defeated presidential candidates, and warned the West to stop backing rioters.

Iranian authorities have accused Western powers of supporting the widespread street protests, and have not ruled out expulsions of some European ambassadors.

Iranian state television said 10 people were killed and more than 100 others wounded in demonstrations held in Tehran on Saturday in defiance of a warning from Supreme Leader Ayatollah Ali Khamenei.

VANDALS BLAMED

Authorities pinned the blame for the weekend deaths on unknown vandals. The office of Tehran's prosecutor general was quoted by Press TV, Iran's English-language television channel, as saying these vandals had opened fire on civilians and killed people on Saturday.

The tough warning by the Guards came after the capital had passed its most peaceful night since the June 12 election.

Young supporters of Mousavi urged people to carry black candles with green ribbons on Monday to demonstrate solidarity with victims of unrest, their website said.

It also encouraged motorists to turn on their headlights for two hours from 5 p.m. (1230 GMT) to show their solidarity with families of martyrs killed in recent events.

The unrest in Iran, a major oil and gas producer, is the most widespread since the 1979 Islamic Revolution, which ousted the U.S.-backed shah. The authorities reject charges of election fraud.

But a spokesman for Iran's top legislative body, which is looking into complaints by the defeated election candidates, conceded that in some constituencies the number of votes had surpassed eligible voters.

Based on initial information, 50 towns had this problem, Guardian Council spokesman Abbasali Kadkhodai was quoted by state broadcaster IRIB as saying on Sunday evening.

He said this might be due to Iranians being able to vote wherever they want, as well as other factors. He said inspectors would look into the issue.

However, the total votes in these constituencies do not exceed 3 million and consequently will not have any impact on the election, he said.

ICON OF PROTEST

Iranians on social networking sites called for mourning for 'Neda', a young woman shot dead on Saturday. Footage of her death has been watched by thousands on the Internet and her image has become an icon of the protests.

We will gather on the streets of Tehran with candles to bear witness and mourn for Neda and other fallen friends, said one posting from Tehran.

Iran continued to accuse the West of supporting rioters.

The promotion of anarchy and vandalism by Western powers and media is by no means acceptable, Foreign Ministry spokesman Hassan Qashqavi told a news conference.

He also said Iranian diplomatic missions had been damaged in protests in other countries, including Germany. British Foreign Secretary David Miliband said foreign countries had played no part in supporting the violent post-election street protests.

U.S. President Barack Obama, at the forefront of diplomatic efforts to halt an Iranian nuclear program the West fears could yield atomic weapons, has urged Iran to stop violence against protesters.

Germany has called for an election recount.

Government restrictions prevent correspondents working for foreign media from attending protests to report.

Pro-reform clerics have increased pressure on Iran's conservative leadership.

Mohammad Khatami, a Mousavi ally and a moderate former president, warned of dangerous consequences if the people were prevented from expressing their demands in peaceful ways.

His comments, carried by the semi-official Mehr news agency, were implicit criticism of Khamenei, who has backed a ban on protests and defended the outcome of the election.

State television said a daughter of former president Akbar Hashemi Rafsanjani, a rival of Ahmadinejad, had been released after being detained together with four other relatives during the Saturday rally in Tehran.

(Additional reporting by Zahra Hosseinian, Hossein Jaseb and Hashem Kalantari; Writing by Richard Balmforth)