TEHRAN - Iran's top prosecutor called on Monday for firm action against people 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 called on 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 on Monday, 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, 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 presidential elections last June.

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

PEOPLE'S RIGHTS

Kaleme is run by allies of Mirhossein Mousavi, an opposition leader who also lost out to President Mahmoud Ahmadinejad in the disputed June vote.

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.

Rejecting accusations by the authorities that the opposition had disrespected Ashura, Karoubi said hardliners felt lonely and isolated and accused them of preparing another pre-planned scenario. He did not elaborate.

Another leading reformer, former president Mohammad Khatami, called for efforts to curb extremism, saying this would help calm the society, ILNA news agency reported.

Like Karoubi he reiterated support for the Islamic system of government, countering allegations by hardline foes that the opposition wants to topple the clerical leadership.

Our demand was to completely implement all parts of the constitution, including ... articles referring to people's rights, he told a group of former lawmakers.

The stakes in Iran's domestic turmoil are high because Ahmadinejad has championed a nuclear energy policy that has led the country, a major oil producer, into dispute with the West.

Iran rejects U.S. charges that it plans to develop nuclear weapons, saying its program is aimed at producing electricity.

(Writing by Fredrik Dahl; editing by Dominic Evans)