Iran's parliament is set to summon President Mahmoud Ahmadinejad for questioning over an economic scandal and his polices after the required number of lawmakers signed a petition Sunday, the latest salvo in a long battle between the president and his rivals.

Ahmadinejad would be the first president to be hauled before the Iranian parliament, a serious blow to his standing in the conflict involving the president, lawmakers and Iran's powerful clerics.

At least 73 lawmakers signed the petition to question Ahmadinejad, just above one-quarter of the 290 members required by Iran's constitution to call in a president.

Earlier the parliament found Ahmadinejad's economics minister guilty in relation to a $2.6 million fraud case, considered the largest in Iran's history.

This is just one of several economic misconduct cases that target Ahmadinejad allies, evidence that his political struggles are a factor. Ahmadinejad has been wrestling with the parliament and the clergy over in the run-up to parliamentary elections in March and a presidential election in 2013.

Ahmadinejad has come under increasing attacks in recent months from the same hard-liners who brought him to power.

Dozens of Ahmadinejad's political backers have been arrested or hounded out of the public eye by hard-line forces in recent months. His protege and top aide, Esfandiar Rahim Mashaei, has been effectively blackballed from his goal of succeeding Ahmadinejad in 2013 elections by a series of reputation-killing accusations.

They include leading a "deviant current" that seeks to challenge the system of theocratic rule, and alleged links to the $2.6 billion bank fraud.

The questioning, should it happen, would be a serious blow to Ahmadinejad, who has already been weakened after he publicly challenged Khamenei in April over the choice of intelligence minister.

The $2.6 billion fraud case involving top government officials has reinvigorated efforts by lawmakers to seriously bring Ahmadinejad before the house, AP reported.