IRAN'S Guardian Council has announced its "final decision" on the disputed June 12 presidential election, dismissing all opposition complaints of fraud and affirming a landslide victory for the President, Mahmoud Ahmadinejad.

The decision was greeted by a loud eruption of the night-time rooftop chanting that has become a hallmark of opposition protests amid an intensifying government crackdown.

Before the announcement, security forces, including members of the pro-government Basij militia, deployed in large numbers to prevent street protests, witnesses said.

Even so, more than a thousand opposition protesters tried to form a human chain by silently linking hands along Vali Asr Street, the capital's longest thoroughfare. They were dispersed by riot police flailing batons and heavy electrical cables, witnesses said.

After the Guardian Council's decision was announced on the 10pm television news, opposition cries of "Allahu akbar" ("God is great") - and "Down with the dictator" echoed across Tehran's rooftops.

The council, a 12-member body that oversees elections and certifies results, made the announcement after conducting a partial recount in an effort to mollify opponents who charge that the President benefited from massive vote-rigging.

In a letter to the Interior Minister, Sadegh Mahsouli, the head of the Guardian Council said members had reached their "final decision" on the election results after an extended review, Iran's state television and radio network reported. "The Guardian Council, after studying the issues … in numerous sessions, dismisses all the complaints received and approves the accuracy of the 10th presidential election," said the letter from Ayatollah Ahmad Jannati.

The recount of 10 per cent of ballot boxes went ahead over the objections of two opposition presidential candidates, who demanded the election be annulled and refused to participate in a special committee set up by the Guardian Council.

The two, the former prime minister Mir Hossein Mousavi and the cleric Mehdi Karroubi, refused to present their complaints to the special committee. Their spokesmen said it would be biased and its review not sufficiently broad. A last attempt by the council to bring Mr Mousavi before the committee on Monday also failed, authorities said.

Referring to the council decision, the US Secretary of State, Hillary Clinton, said in Washington: "Obviously, they have a huge credibility gap with their own people … and I don't think that's going to disappear by any finding of a limited view of a relatively small number of ballots."