AFP - Hardline incumbent Mahmoud Ahmadinejad was on Saturday declared winner by a landslide in Iran's hotly-disputed presidential vote, triggering riots by opposition supporters and furious complaints of cheating from his defeated rivals.
Ahmadinejad went on television to declare the election a "great victory," even as baton-wielding police were clashing with protestors in the streets of the capital in unrest not seen for a decade.
Thousands of supporters of main challenger Mir Hossein Mousavi swept through Tehran shouting "Down with the Dictator" after final results showed Ahmadinejad winning almost 63 percent of the vote.
Moderate ex-premier Mousavi cried foul over election irregularities and warned the outcome of the vote could lead to "tyranny," as some of his supporters were beaten by riot police.
Ahmadinejad however rejected the allegations.
"The election was completely free... and it is a great victory," he said in his television address.
The interior minister said Mousavi had won less than 34 percent of the vote, giving Ahmadinejad another four-year term in a result that dashed Western hopes of change and set the scene for a possible domestic power struggle.
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.
The vote outcome appears to have galvanised a grass-roots movement for change after 30 years of restrictive clerical rule in a country where 60 percent of the population was born after the revolution.
The international community had also been keenly watching the election for any signs of a shift in policy after four years of hardline rhetoric from the 52-year-old Ahmadinejad and a standoff over Iran's nuclear drive.
Mousavi 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.
"No one can imagine such rigging, with the world watching, from a government who holds commitment to shariah-based justice as one of its basic pillars," said Mousavi said in a letter posted on his campaign website.
"What we have seen from dishonest (election) officials will result in shaking the pillars of the Islamic republic system, and a dominance of lying and tyranny," he said in a separate statement.
In the heart of Tehran, thousands of Mousavi supporters voiced their disbelief and frustration at the results, with some throwing stones at police who struck back with batons.
Angry crowds first emerged near Mousavi's campaign office in central Tehran, where protestors, including women, were hit with sticks as riot police on motorbikes moved in to break up the gathering, an AFP correspondent said.
While crowds continued to There were no immediate reports of violence elsewhere in the county.
Reformist candidate Mehdi Karroubi, who came a distant fourth with less than one percent of the vote after ex-Revolutionary Guards chief Mohsen Rezai in third, also declared the result "illegitimate and unacceptable".
"They have ruined the country and they want to ruin it more over the next four years," shouted an irate mob outside Mousavi's office.
The White House said Saturday it was monitoring the reports of irregularities, while Canadian Foreign Minister Lawrence Cannon said he was "deeply concerned" about the allegations.
US Secretary of State Hillary Clinton, meanwhile, said she hoped the result of the election "reflects the genuine will and desire of the Iranian people."
In Moscow, the chairman of the Duma (parliament) Committee on International Affairs Konstantin Kosachev hoped for more "understanding and wisdom" from Ahmadinejad in the new term.
Khamenei hailed Ahmadinejad's victory as a "feast."
"The enemies may want to spoil the sweetness of this event... with some kind of ill-intentioned provocations," he said. "The president elect is the president of the entire Iranian nation and... all should support and help him."
Mousavi had been hoping for a political comeback on a groundswell of support among the nation's youth, with pledges to ease restrictions particularly on women, and fix Iran's ailing economy.
Ahmadinejad's supporters had earlier taken to the streets in triumph, honking their horns and waving Iranian flags.
The election highlighted deep divisions in Iran after four years under Ahmadinejad, who had massive support in the rural heartland, while in the big cities young men and women threw their weight behind Mousavi.
The elite Revolutionary Guards had warned of a crackdown on any "velvet revolution" by supporters of the 67-year-old who was prime minister during the war with neighbouring Iraq in the 1980s.
Iran has long been at loggerheads with the West as Ahmadinejad delivered a succession of fiery tirades against Israel, repeatedly questioned the Holocaust and vowed to press on with nuclear work despite UN sanctions, denying allegations Tehran was seeking the atomic bomb.
"The results of the election show, now more than ever, how much stronger the Iranian threat has become," said Israel's deputy foreign minister Danny Ayalon.