Iranian authorities closed down pro-reform cleric Mehdi Karoubi's office today, Iranian news agency ILNA reported, and a website said one of his top aides was detained.
Judiciary officials entered Mr Karoubi's office in northern Tehran and told him and others inside to leave, ILNA said, adding documents, discs and other material were seized.
"Karoubi's office has been sealed off upon the Tehran prosecutor's order," it quoted Esmail Gerami-Moghaddam, a spokesman for Mr Karoubi's party, as saying. Karoubi came fourth in June's disputed presidential election.
There was no immediate comment from Iranian officials.
Website mowjcamp.ir said agents raided and searched the home of Morteza Alviri and took him away. It also confirmed the closure of Karoubi's office.
Security forces yesterday raided an office run by allies of opposition leader Mirhossein Mousavi, the election runner-up, and confiscated documents, his website said.
Mr Mousavi's website said it was the premises of a committee set up by him to look into post-election events, including the number of dead and the treatment of people detained during the huge opposition demonstrations that followed the vote.
Mr Karoubi, whose newspaper was closed down three weeks ago, angered hardliners last month by saying some imprisoned protesters were raped and abused in jail.
The authorities have rejected the allegation as baseless but the judiciary and parliament have agreed to look into the issue.
Supreme Leader Ayatollah Ali Khamenei ordered the closure of Tehran's Kahrizak detention centre in July after reports of abuse there and the semi-official Mehr News Agency said a trial of people involved would start in coming days.
Mr Karoubi said on his party's website this week he had handed over films and other material about abuse of three detainees to a special investigative parliamentary committee.
Mr Ahmadinejad has suggested his opponents were behind any such incidents, saying they had "infiltrated" government forces.
The election and its turbulent aftermath plunged Iran into its deepest internal crisis since the 1979 Islamic revolution, exposing deepening divisions within its ruling elites and adding to tension with the West.
Reformist leaders say it was rigged to secure Mr Ahmadinejad's re-election. He denies the charge, describing it as the healthiest vote ever held in the Islamic Republic.
The protests were put down by the elite Revolutionary Guards and a pro-government Islamic militia, but pro-reform leaders have made clear they will continue their fight over the poll.
The opposition says more than 70 people were killed in the unrest. The authorities estimate the death toll at 26 people and say members of the Islamic Basij militia were among them.
Hardliners have portrayed the opposition protests as a foreign-backed bid to undermine the Islamic government system.
Reuters