Italy's main opposition parties called on Prime Minister Matteo Renzi to resign on Friday, a day after his industry minister stepped down over allegations she added an amendment to the budget to benefit her boyfriend's business interests.

Economic Development Minister Federica Guidi quit on Thursday, hours after Italian investigators released wiretapped conversations in which she tells her partner, Gianluca Gemelli, that an amendment that had not yet been made public would be approved.

Guidi said in a letter to the premier that she had quit for "political reasons."

Economic Development Minister Federica Guidi denied any wrongdoing.

The amendment would help Gemelli's engineering business win contracts with French oil giant Total in its plans to develop the Tempa Rossa oil field by not requiring permits from two Italian regions opposed to their development.

Gemelli, who is under criminal investigation on suspicion he abused his personal connections, later told Total "the good news."

Questions whole government

Italy's opposition jumped on the scandal to attack Renzi's government, which ran on a platform to end cronyism and battle corruption.

"This matter calls into question the whole government... It always puts people in charge who are in the pay of the lobbies or who are looking out for themselves," said Luigi Di Maio of Italy's second-largest party, the 5-Star Movement.

It is unclear when the opposition plans to hold the no-confidence vote, but they are demanding that Renzi's ally Maria Elena Boschi, the minister for parliamentary relations, also resign over allegations she conspired with Guidi.

The wiretapped conversation reveals that Guidi told her boyfriend that Boschi had assured her the amendment would pass.

"The news is not that minister Guidi has resigned, but that minister Boschi has not," said Renato Brunetta, parliamentary chief of the center-right Forza Italia party.

Boschi overcame calls to resign in December after a banking scandal, while Infrastructure Minister Maurizio Lupi resigned last March over a scandal in allocating public contracts.

Bad news ahead of June elections

Renzi, who look over as premier two years ago, is likely to survive a no-confidence vote, but the scandal could hurt his party in June local elections at a time when the economy is also stagnating.

The scandal broke from an original investigation into the illegal disposal of liquid waste from an oil extraction plant in southern Italy.

Six employees at the facility were arrested on Thursday for allegedly disposing of toxic waste that they disguised as harmless. Italian energy firm ENI has suspended production at the facility in response.

cw/jm (AFP, Reuters)