France's Francois Fillon on Thursday denied claims his wife was paid for a fake job and stated the allegations were attempts to harm his presidential bid.
Fillon, a 62-year old conservative former prime minister, added that the allegations only strengthened his resolve to run in the upcoming election.
Satirical weekly Le Canard Enchaine had reported on Wednesday that Penelope Fillon had been paid some 600,000 euros ($645,000) for many years of employment as a parliamentary assistant to Fillon.
The newspaper said its research had shown there was no evidence she had ever actually worked.
"My wife has been working for me forever, ever since I first got elected in 1981," Fillon told TF1 television, adding that she did it for free for a long time before he hired her in 1997 as parliamentary assistant.
"The question is why -- while my wife had been paid from 1997 -- this comes out now, two and a half months before the election? Clearly, this is to try and take me down as a presidential candidate."
TRT World's Myriam Francois has more details.
Fillon is the conservative frontrunner in this spring's election, but the allegations about his wife Penelope have rattled the campaign of a man who has pitched himself to voters as an honest and morally irreproachable candidate.
Fillon had until now been seen on a fairly smooth trajectory towards the Elysee - the election will be held in two stages, on April 23 and May 7 - despite a strong challenge from far-right party leader Marine Le Pen and from centrist Emmanuel Macron.
A lawyer for Francois Fillon went to the financial prosecutor's office on Thursday to present evidence, after prosecutors opened an inquiry the day before for misuse of public funds following the Canard Enchaine story.
The opening of a preliminary investigation is a first step in the judicial process and does not mean that either Fillon or his wife will eventually be charged or even placed under formal investigation.
"Yes I will run in the (presidential) election," Fillon said, adding that "the only thing" that could stop him from being a candidate was if he was put under formal investigation.