Brest, France,: French prosecutors said Thursday they had launched a preliminary investigation into a property deal involving one of President Emmanuel Macron’s ministers, on the same day his new government outlines a bill on cleaning up politics.

The announcement by prosecutors in western France adds to the pressure on Richard Ferrand, who has rebuffed calls to resign over allegations of favouritism towards his common-law wife in a lucrative deal with a health insurance fund.

The affair has embarrassed 39-year-old Mr Macron, who swept to power on May 7 on a pledge to rejuvenate France’s corruption-plagued political class — a win he aims to cement in June’s parliamentary elections.

It comes as justice minister Francois Bayrou prepares to set out the contents of the President’s first highly-anticipated bill, which will tighten ethical standards for holders of public office.

Mr Ferrand, one of Macron’s first prominent backers and formerly secretary general of the President’s Republique En Marche party, has denied any wrongdoing. He told France Inter radio on Wednesday: “I am an honest man.” “Everything I have done in my professional life is legal, public and transparent,” he insisted.

Mr Ferrand, a 54-year-old minister for territorial cohesion who is running for re-election to parliament, says Doucen made the fund the best offer and that he had no say in the matter.