TEHRAN, Iran—Iran has arrested a senior government official, two years after a parliamentary probe found him responsible for deaths by torture of at least three jailed anti-government protesters.

State media say Saeed Mortazavi—an ally of President Mahmoud Ahmadinejad—was taken to Tehran's Evin prison late Monday night but gave no details.

Mortazavi was Tehran city prosecutor in 2009. At the time, he was responsible for Kahrizak prison, where at least three anti-government protesters were tortured to death. He now heads the country's social security fund.

Iran's reformists have openly criticized Mortazavi during his years in the judiciary. He was even dubbed "butcher of the press" for the closures of more than 120 newspapers and the imprisonment of dozens of journalists and political activists over the past 13 years.