PARIS (AFP) - Lawyers for French presidential candidate Francois Fillon on Thursday (Feb 9) called on prosecutors to drop their probe into payments made to his wife for a suspected fake job, calling it "illegal".

The lawyers said the two-week-old probe into the payments to Penelope Fillon, who was hired by her husband as a parliamentary aide, was "invalid" and "completely tramples democratic principles".

The investigation dealt a "serious blow to the principle of the separation of powers" between the judiciary and the legislature, lawyer Antonin Levy told a press conference.

Levy and fellow lawyer Pierre Cornut-Gentille argued that Fillon enjoyed discretion in the use of funds available to him as an MP and that the probe into misuse of public money was therefore "totally inapplicable".

"The absence of such an offence makes the financial prosecutor's office incompetent to investigate and the investigation is therefore illegal," Levy said.

He also criticised constant leaks about the investigation to the media which he said were damaging to his client and likely to have an impact on the two-stage presidential election in April and May.

"The financial prosector's office has a responsiblity. It's important that voters don't have their election stolen in April," Levy added.

Fillon's presidential bid has been thrown into turmoil by the revelations that his wife was paid hundreds of thousands of euros over 15 years for a role she is suspected of not having fulfilled.

The conservative former prime minister, who had been leading the race before the story broke, has denied any wrongdoing.