Security forces have raided the office of Iran's top opposition leader and seized computers after days of intimidating visitors with a heavy force presence around the building.
The raid on Mirhossein Mousavi's office on Wednesday night points to a stepped-up campaign to harass the leaders of the country's besieged and dispirited pro-reform movement.
Relentless crackdowns over the past year have driven opposition activists from the streets after an initial outpouring to protest against the June 2009 presidential election, which they say was fraudulent.
Earlier this month, pro-government mobs attacked the home of another opposition leader, Mahdi Karroubi, with homemade bombs and beat a bodyguard unconscious.
Security forces have been deployed around Mr Mousavi's office for several weeks, said the report on the Kaleme website. The head of Mr Mousavi's office, Hamid Mohseni, was arrested on Monday, it said. Mr Mousavi was not in his office when it the raid took place.
Mr Mousavi and Mr Karroubi are the two pro-reform candidates who ran against President Ahmadinejad in 2009. Mr Mousavi said he was the rightful winner of the vote, and tens of thousands of Iranians poured into the streets to challenge Mr Ahmadinejad's re-election and ultimately the ruling system itself.