By Siavosh Ghazi

TEHRAN (AFP) — Iran has rounded up at least 10 reformist leaders, a party member said, after President Mahmoud Ahmadinejad’s re-election in a deeply-disputed vote sparked riots across Tehran.

Ahmadinejad appeared on television on Saturday to declare his landslide victory over moderate challenger Mir Hossein Mousavi was “fair” after thousands of angry opposition supporters took to the streets in protest at alleged vote-rigging.

Iranian security forces have arrested at least 10 leaders of two reformist groups who backed ex-premier Mousavi in Friday’s vote, an official from one group told AFP.

“At least 10 members of the Islamic Iran Participation Front and the Islamic Revolution Mujahedeen Organisation were arrested yesterday,” said Rajab Ali Mazroei, a member of the front.

Thousands of Mousavi supporters swept through Tehran on Saturday shouting “Down with the Dictator” after final results showed the hardline incumbent Ahmadinejad winning almost 63 percent of the vote.

Baton-wielding riot police firing tear gas clashed with protestors who pelted security forces with stones and set rubbish bins and police vehicles ablaze in unrest not seen since student riots a decade ago.

“The election was completely free… and it is a great victory,” Ahmadinejad, 52, said in his television address, calling on his supporters to gather on Sunday in a Tehran square where many of the clashes occurred.

Mousavi cried foul over what he branded a “rigged” vote and a “charade” and said it could lead to tyranny in the Shiite-dominated nation, which has lived under clerical rule since the Islamic revolution three decades ago.

But he had called on his supporters to stay calm and show restraint after official results showed he had secured less than 34 percent of the vote despite some expections he would win enough to go through to a second-round runoff.

The election results dashed Western hopes of change after four years under the combative Ahmadinejad, who set the country on a collision course with the West over its nuclear drive and his anti-Israeli tirades.

Iran’s all-powerful supreme leader Ayatollah Ali Khamenei hailed Ahmadinejad’s victory and urged the country to unite behind him after the most heated election campaign since the Islamic revolution in 1979.

However the vote outcome appears to have galvanised a grass-roots movement for change in the Islamic republic, where 60 percent of the population was born after the revolution.

The international community reacted cautiously to the vote outcome and the allegations of vote irregularities.

“The United States has refrained from commenting on the election in Iran. We obviously hope that the outcome reflects the genuine will and desire of the Iranian people,” US Secretary of State Hillary Clinton said.

The United States is “monitoring the situation as it unfolds in Iran,” she added.

New US President Barack Obama has called for dialogue with its arch-foe after three decades of severed ties, a major policy shift following his predecessor George W. Bush’s description of Iran as part of an “axis of evil.”

The European Union said it was “concerned about alleged irregularities during the election process and post-election violence.”

Israel voiced concern over the return of Ahmadinejad, who has caused international outrage by repeatedly describing the Holocaust as a myth and calling for the Jewish state to be wiped off the map.

“The results of the election show, now more than ever, how much stronger the Iranian threat has become,” Israeli deputy foreign minister Danny Ayalon said.

Mousavi had protested at what he described as “numerous and blatant irregularities” in the vote which officials said attracted a record turnout of around 85 percent of the 46 million electorate.

The election highlighted deep divisions in Iran after four years under Ahmadinejad, who had massive support in the rural heartland and among the poor, while in the big cities young men and women threw their weight behind Mousavi.

As the protests intensified on Saturday, Iran’s main cellular phone network was cut and social networking site Facebook was also blocked.

Police beefed up their presence in main streets and squares of the capital, especially in the area housing Mousavi’s campaign office, while dozens of men were seen handcuffed and detained in an interior ministry compound.

Members of Iran’s volunteer Basij militia were also deployed in some parts of the city while smouldering garbage cans were lying on pavements after being set ablaze by rioters.