AFP - Iranian opposition leader Mehdi Karroubi called on his supporters on Wednesday to peacefully participate in next week's rally marking the 31st anniversary of the Islamic revolution, as authorities threatened to crack down on any protests.

Karroubi's call came after the judiciary executed two people last week and said nine more are to be hanged on charges of taking part in anti-government rallies and plotting to topple the regime.

"Let us all together take part in the anniversary rally calmly and firmly... with patience and without verbal and physical violence," Karroubi said in a statement carried by his website Sahamnews.org.

He warned his supporters that "enemies of your peaceful movement" wanted to provoke them into "breaking the norms."

Opposition supporters have repeatedly taken advantage of state-sponsored events like the February 11 revolution anniversary rally to hold anti-government protests as the authorities have refused them permission to organise events of their own.

Dozens of people have been killed in clashes between protesters and the security forces since the disputed re-election of hardline President Mahmoud Ahmadinejad last June.

Karroubi renewed his accusation that the "people's vote was engineered" in the election and asked the authorities to "put an end to the atmosphere of intimidation."

He urged people not to "deviate from their rightful and legitimate demand" for free elections, the release of political prisoners, correction of the system of government and respect for the rights of citizens.

Hundreds of thousands of Iranians march each year to commemorate the revolution which toppled the pro-Western shah in 1979.