Opposition supporters, who allege systematic fraud, have demanded a new election and have staged near-daily protests challenging the claim that hardline President Mahmoud Ahmadinejad won re-election by a landslide.

With Tuesday's announcement, Iran's regime appeared to be closing another door to compromise. Iran's supreme leader had already praised Ahmadinejad as the winner and ordered post-election protesters off the streets. On Monday, the feared Revolutionary Guard threatened a crackdown if protests persist.

Such threats and the deaths of at least 17 people since the start of the protests have prompted growing concern by the international community about the fate of opposition supporters. In New York, U.N. Secretary Ban Ki-moon urged an "immediate stop to the arrests, threats and use of force," U.N. spokeswoman Michele Montas said at U.N. headquarters Monday.

The announcement by the Guardian Council came a day after it said _ in a rare acknowledgment _ that there had been voting irregularities in 50 districts, including local vote counts that exceeded the number of eligible voters. However, the council said the discrepancies were not widespread enough to affect the result. The council agreed last week to investigate opposition complaints of problems in the voting.

The council found "no major fraud or breach in the election," a spokesman, Abbas Ali Kadkhodaei, was quoted by Iran's state-run English language Press TV as saying.

"Therefore, there is no possibility of an annulment taking place," he said.

Ahmadinejad's main challenger, Mir Hossein Mousavi, has charged the election was a fraud and insists he is the true winner.

In a sign of a growing crackdown, Tehran riot police fired tear gas and live bullets Monday to break up about 200 protesters paying tribute to a young woman whose apparent shooting death was captured on video and circulated worldwide.

A man identifying himself as the woman's boyfriend later said he had tried to dissuade her from attending the protests because of the risk, but that she told him she wanted democracy and freedom for the people of Iran.

Severe restrictions on reporters have made it almost impossible to independently verify reports on demonstrations, clashes and casualties. Iran has ordered reporters for international news agencies to stay in their offices, barring them from reporting on the streets.