A French court has opened an investigation into Justice Minister Eric Dupond-Moretti for alleged conflict of interest relating to his time as a lawyer, prosecutors told AFP on Wednesday.

The Court of the Republic, which deals with cases involving suspected misconduct by sitting cabinet members, launched the probe after complaints by Anticor, an anti-corruption association, and three magistrates' unions.

The allegations centre on an administrative investigation ordered by Dupond-Moretti against three prosecutors working at the financial crimes prosecutor's office.

The three were part of a team trying to find a mole who may have warned former president Nicolas Sarkozy and his lawyer Thierry Herzog that their phones were being tapped as part of a corruption inquiry.

The investigators checked the phone records of Dupond-Moretti among others, who was a criminal defence lawyer at the time and not yet a minister, and who filed a complaint against them.

His decision to order an inquiry after joining President Emmanuel Macron's cabinet prompted allegations that he may have used his new post to settle scores.

"I have nothing to fear," Dupond-Moretti said in response to questioning during a Senate panel debate on justice proceedings for minors.

"I followed the recommendations of my administration, and I will prove it," he said, adding: "My crime is having carried out my functions exactly as my predecessors would have done in similar circumstances."

Separately on Wednesday, the financial crimes office said it had launched a preliminary investigation into another minister, Sebastien Lecornu, also for conflict of interest.

The probe into Lecornu, who is responsible for France's overseas territories, centres on his time as head of the northern French Eure department, the office's prosecutors told AFP.

The investigation is to determine whether Lecornu was within the law when he accepted remuneration as a board member of the Paris-Normandy motorway operator SAPN in 2016 and 2017 while also, as head of the department, having great influence over public contracts awarded to SAPN.

Contacted by AFP, Lecornu's office said he had done his job "in all transparency", and had declared it to the authority in charge of vetting potential conflicts of interest among public servants.

The minister's office also noted that it was common practice for heads of departments to be on the boards of motorway operators.

gd/jh/js/pvh