Iran's top prosecutor called yesterday for firm action against those behind street unrest after the Islamic Republic's disputed election in June, in a clear warning that senior opposition figures may face trial.

General-prosecutor Gholamhossein Mohseni Ejei made the call for measures against "elements behind the recent sedition" in a statement to Tehran chief prosecutor Abbas Jafari Dolatabadi, the Isna news agency reported.

Referring to a petition signed by clerics in Tehran, he said, without giving any names: "It is expected that the demands... that those who were leading the post-election sedition are put on trial, are met."

Hardline clerics and authorities have urged the judiciary to punish opposition leaders for igniting tension in Iran, saying they were mohareb, an Islamic term meaning warring against God which carries the death penalty.

But senior opposition politician Mehdi Karoubi said threats would not stop his pro-reform path, three days after an opposition website said shots had been fired at a car he was in.

In a defiant statement posted on the Sahamnews website of his party Etemad-e Melli earlier yesterday, Mr Karoubi said he and his family were "prepared for any disaster".

"Some are thinking that they can block the reform course by closing down newspapers and putting reformers in jail... but I remain firm in the path that I have chosen," Mr Karoubi said.

"I announce that such threats will not frighten me and will not weaken me in this path," added the reformist cleric, a defeated candidate in the poll last June which was won by hardline President Mahmoud Ahmadinejad.

On Friday, the opposition Kaleme website said unidentified men had opened fire on Mr Karoubi's car in the city of Qazvin, an incident later denied by a senior police official. Mr Karoubi did not mention the reported incident in his statement yesterday.

Iran has seen its most serious domestic unrest since the Islamic revolution in 1979, as opposition supporters stage protests against the election result that have turned violent. Authorities deny opposition charges that voting was rigged.

Eight people were killed in clashes between security forces and opposition supporters on Ashura, the day of ritual Shi'ite mourning that fell on December 27.

The opposition website Rahesabz said last week that more than 180 people, including 17 journalists and 10 Mousavi aides, had since been arrested. More than 80 people who were detained after the June vote had earlier been jailed for up to 15 years.

The post-election turmoil has exposed widening divisions in the political establishment of the major oil producer.