The release of Saeed Mortazavi, reported by two Iranian news agencies, came as the latest chapter in several days of political drama playing out with prominence in the public eye.
During a Sunday session of Parliament, broadcast on state radio, Mr. Ahmadinejad singled out the head of the Parliament, Ali Larijani, a political rival with strong links to influential Shiite Muslim clerics and one of several brothers who have held top positions in the Iranian government.
His younger brother Sadegh, 52, heads Iran’s judiciary, while his oldest brother, Mohammad Javad, a Berkeley-educated mathematician, is also a judiciary official.
On Monday, a conservative newspaper, Kayhan, hinted that the nation’s supreme leader, Ayatollah Ali Khamenei, had been forced to step in to prevent both men from giving potentially damaging news conferences, which were both canceled at the last minute.
This was not the first time Ayatollah Khamenei has been forced to intervene in this feud. In October, he issued an edict aimed at stopping the infighting, saying that those creating divisions before the June 14 presidential elections “betray” the country.
Mr. Ahmadinejad, who went to the Parliament in a failed attempt to head off the impeachment of his labor minister, Abdolreza Sheikholeslami, said Mr. Larijani and his fellow lawmakers had obstructed the government, stepped beyond their constitutional boundaries and written letters ordering the annulment of government decisions.
Instructed by Mr. Larijani to stick to the subject of the impeachment, Mr. Ahmadinejad said, “Don’t order me to close my mouth because you say it’s the law.”
With that, Mr. Ahmadinejad, who for years has threatened to reveal the names of corrupt officials, played a video clip of a conversation in which another of Mr. Larijani’s brothers, Fazel, appeared to discuss the purchase of a state company under favorable terms, the semiofficial Tabnak Web site reported. While Fazel Larijani used to head a medical association in Iran, his current position is unclear.
The public accusation, rare in Iran, could signal a new phase in an already intense conflict between Mr. Ahmadinejad, who represents a powerful group of young, ambitious politicians, and Mr. Larijani, who is the official representative of the holy city of Qum, the center of Shiite scholarship in Iran.
Mr. Ahmadinejad said his associate, Mr. Mortazavi, 45, was also at the taped meeting. In January, Mr. Mortazavi was dismissed as the head of Iran’s enormous social welfare organization under pressure from Parliament. Some days later, however, he was rehired by the president in the same position, this time as official caretaker.
During the conversation, read out in part by Mr. Ahmadinejad to astonished lawmakers, Fazel Larijani appears to try to use his family connections to buy a factory from the social welfare organization. He promises leniency for Mr. Mortazavi, the former Tehran prosecutor who faces several criminal proceedings over accusations that he played a role in the deaths of three protesters in a substandard prison in 2009.
Mr. Mortazavi was arrested Monday evening, the Fars news agency reported, though no reason was given. But, in a new turn to what is likely to be a protracted saga, he was freed on Wednesday, news reports quoted Iranian media as saying. The terms of his release were unclear.
In Parliament on Sunday, the Iranian Students’ News Agency said, Mr. Ahmadinejad declared: “These are audio and video, and the tape is clear.”
He added: “If the honorable Parliament speaker sees fit, we can turn over the 24 to 25 hours to you,” he said of the recordings. On Monday, Iran’s Islamic Republic News Agency, a mouthpiece for Mr. Ahmadinejad, deepened the split by publishing the audiotape on its Web site.
Ali Larijani, cheered on by the Parliament, which has lost nearly every serious political battle with the president, silenced the room, saying: “Let him tell his words. If there is anything about my family, then let him talk about it.”
Mr. Larijani called the video a “mafia film” and recalled how he had a meeting with Mr. Ahmadinejad’s estranged brother, Davoud. “He said many things against you,” Mr. Larijani told the president, “about economic corruption, about your inner circle and your relations with foreign countries.”
For his part, Fazel Larijani strongly denied any wrongdoing, saying that while he did appear in the clip, the words were not his, but rather had been added in a voiceover. Calling Mr. Ahmadinejad and Mr. Mortazavi “mafialike individuals,” he said he would sue them both for “spreading lies and disturbing public opinion.”
On Monday, several officials criticized Mr. Ahmadinejad and Ali Larijani, accusing them of lacking self-control and bringing shame on the country. “They broke the leader’s heart and gave the friends of the Islamic republic almost a seizure,” said Mojtaba Zolnour, a special consultant to the supreme leader, Ayatollah Khamenei, the semiofficial Iranian Labor News Agency reported. “They provided ammunition for the foreign media on the eve of our election.”
Alan Cowell contributed reporting from Paris.