Iran's new judiciary chief has replaced a hardline prosecutor who played a key role in the mass trials of leading reformers arrested over unrest that erupted after a disputed presidential election in June.

The move by judiciary chief Ayatollah Sadeq Larijani is likely to be welcomed by moderates who also blame Tehran prosecutor Saeed Mortazavi for shutting down many pro-reform newspapers during his time in office.

But it was unclear whether it would have any impact on the trials of more than 100 senior pro-reform figures, activists and others charged with inciting post-election protests. Four such mass trials have been held in a Tehran court this month.

The official IRNA news agency, in a report on Saturday evening, said Mortazavi had been replaced by Abbas Jafari Dolatabadi as Tehran's public prosecutor.

It did not give a reason for the decision by Larijani, who took office earlier this month. Judiciary sources had told Reuters that Larijani had made Mortazavi's replacement a condition for accepting the judiciary chief post.

"Abbas Jafari Dolatabadi has been appointed as new Tehran public and revolutionary prosecutor," IRNA said, citing Larijani's public relations office.

IRNA said Larijani had also formed a "supervisory board" to look into post-election events, including detainees' rights.

Defeated presidential candidates have said some imprisoned protesters were raped, a charge rejected by the authorities.

Larijani is a brother of parliament speaker Ali Larijani, who ran against hardline President Mahmoud Ahmadinejad in the 2005 presidential election.

Mortazavi signed the indictments against dozens of pro-reform figures put on trial accused of inciting protests in a bid to topple the Islamic establishment after the election.

The opposition and the West have condemned the mass trials, in which a French teaching assistant was also in the dock. No sentences have so far been announced in the trials. - Reuters