Iranian President Mahmud Ahmadinejad has accused the parliament speaker's family of corruption and abuse of power, just months ahead of the country's June presidential election.
Ahmadinejad addressed parliament on February 3 to defend one of his ministers against impeachment proceedings.
The lawmakers impeached and removed Labor Minister Abdolreza Sheikholeslami from office over his recent, controversial appointment of a former chief Tehran prosecutor as the head of Iran's social-security fund.
The appointed official in question is Said Mortazavi. A 2010 parliamentary probe found him responsible for the deaths of at least three antigovernment protesters in Tehran prisons.
During the Majlis (parliament) session on February 3, the president played a recording of what he described as a conversation between Mortazavi and Fazel Larijani, a brother of parliament speaker Ali Larijani and Sadeq Larijani, the head of Iran's judicial system.
The audio was barely audible and Ahmadinejad read out what he called the content of the conversation, saying it implicated the Larijani brothers in corruption.
Ahmadinejad claimed Fazel Larijani was seeking a bribe in return for ensuring political support of both the Majlis and the judiciary in allegedly securing an illegal business deal.
"Here Mr. Fazel Larijani tells Mr. Mortazavi, 'The person, who wants to secure the contract should be cautious, he shouldn't tell anyone anywhere that he has a certain person's support,'" Ahmadinejad said.
Ahmadinejad said he "can turn over the 24 to 25 hours" of recordings to the parliament speaker.
Larijani fired back, saying Ahmadinejad had blocked judicial investigations against his close political allies.
Larijani said Ahmadinejad was trying to use the tape as a "threat" to hamper the impeachment process. He accused the president of a "mafia-type" attitude, and disregarding ethics and dignity.
"By the way, it's good that you, who always say, 'I am going to tell, I'm going to tell,' played this tape here because people will now know your character better," Ali Larijani said.
The statements threw the session into chaos, with angry accusations and jeers shouted across the chamber.
The rift between the president and the conservative-dominated Majlis surfaced in April 2011, when lawmakers questioned Ahmadinejad's dismissal of an intelligence minister.
That dismissal was seen as Ahmadinejad's defiance of Supreme Leader Ayatollah Ali Khamenei, who has final say in all state matters. The minister was subsequently reinstated at the supreme leader's instruction.
In March 2012, the parliament questioned Ahmadinejad over the alleged mismanagement of the nation's struggling economy.
After serving two consecutive terms, Ahmadinejad cannot run in the June election, but analysts say he may try to maintain influence after leaving office.
Ahmadinejad, once a protege of Supreme Leader Ayatollah Ali Khamenei, has fallen out of favor over a power struggle with Khamenei and his allies.
Ali Larijani ran for president in 2005, but has not made a decision about running in June's election.
With reporting by Reuters, Payvand.com, AP, AFP, and RFE/RL's Radio Farda