Earlier more than 200 people gathered at the city's United Nations building to hand over a protest note demanding the world body nullify elections the Iranian opposition allege was rigged.

'We want all the countries in the world not to recognise Ahmadinejad as Iranian president. The election was fraud. The actual winner is (Mir Hossein) Mousavi,' Ali Bozrgmer, a 28-year-old student told AFP.

He said the protest lasted for about one hour during which they shouted slogans such as 'Where is my vote?' and 'Ahmadinejad go to hell'.

The protesters, who were mainly students from the local Iranian community of some 9,000 people, then continued their march along a busy road outside the UN building, he said.

Witnesses said the police warned protesters to end the demonstration before firing tear gas.

'The police gave us warning to disperse. But they suddenly fired several rounds of tear gas. We ran away,' Mr Bozrgmer said, adding that they plan more protests.

Mr Mousavi has lodged a formal protest calling for an annulment of the result of Friday's presidential election, which he lost to hardliner Ahmadinejad, complaining of vote-rigging.

Iranian opposition supporters worldwide have staged demonstrations to protest at the election which returned Ahmadinejad to another four years in power. -- AFP