Iranian police late Monday arrested former Tehran prosecutor Saeed Mortazavi, an ally of President Mahmoud Ahmadinejad, official media reported without stating any reason for the move.
Mortazavi, Tehran's notorious former prosecutor, was suspended in August 2010 along with two other judges over the death in prison of three anti-government protesters in the aftermath of the 2009 presidential election.
A parliamentary probe found Mortazavi responsible for sending protesters to Kahrizak, a detention centre south of Tehran, and demanded that he be punished. The case is still ongoing.
He was at the centre of a raucous parliamentary session on Sunday when the bad blood between Iran's government and parliament spilled into open.
A majority of MPs voted in a heated parliament session, broadcast live on state radio, to remove the labour and social welfare minister, Abdolreza Sheikholeslam, for refusing to sack Mortazavi.
Mortazavi, seen close to President Ahmadinejad, had been appointed as caretaker of Iran's wealthy social welfare organisation.
Sunday's brawl came as Iran gears up for its presidential election on June 14 to find a replacement for Ahmadinejad, whose victory in 2009 sparked protests against poll results which the opposition claimed were rigged.
The rift between Ahmadinejad and parliament, dominated by conservatives critical of his administration, first surfaced in April 2011 after he challenged a ruling by supreme leader Ayatollah Ali Khamenei, who has final say on all state matters.
The dismissal of Sheikholeslam on Sunday marked parliament's second successful unseating of Ahmadinejad's ministers in his second and last term. In February 2011 the then transport minister was dismissed.
During Sunday's feisty debate, Ahmadinejad accused parliament speaker Ali Larijani and judiciary chief Ayatollah Sadegh Larijani of nepotism.
To back his claim, the president played a recording in which a voice said to be of their brother, Fazel, allegedly attempts to bribe Mortazavi by asking for a favour in exchange for political support of both parliament and the judiciary.