The Tehran prosecutor's office has confirmed that controversial former chief Tehran prosecutor Saeed Mortazavi has been arrested.
No reason was given for the arrest.
The Fars news agency said Mortazavi was taken to Evin prison.
Iranian President Mahmud Ahmadinejad denounced the arrest in comments posted on his official website, calling it "a very ugly act."
The arrest came after Mortazavi played a role in a clash in parliament on February 3 between parliament speaker Ali Larijani and Ahmadinejad, who is seen as close to Mortazavi.
The president accused Larijani’s family of corruption in an attempt to defend Labor Minister Abdolreza Sheikholeslami from impeachment over his appointment of Mortazavi as head of Iran’s social security fund.
Parliament voted to remove Sheikholeslami from office.
Mortazavi, accused by rights groups of a series of abuses, was suspended after a 2010 parliamentary probe faulted him over the deaths of at least three antigovernment protesters in prison.