The rightwing Fillon is facing an investigation into claims he handed his British-born wife Penelope a fictitious paid role as a parliamentary aide.
The rightwing Fillon, who polls show is likely to reach the second round of May's election, is facing an investigation into claims he handed his British-born wife Penelope a fictitious paid role as a parliamentary aide.
Fillon's campaign manager, senator Bruno Retailleau, said the candidate's lawyer would contact the national financial prosecutor's office and "take them a certain number of documents".
"We will give all the pieces (of evidence) to the investigators very quickly," Retailleau said.
"It will then be between the investigators and Francois Fillon," he said, adding: "I tell you, this thing is going to fizzle out very quickly."
The allegations are potentially damaging to the 62-year-old, who owed some of his surprise victory over Nicolas Sarkozy in the rightwing primary contest to a "clean" image, contrasting with the former president's legal woes.
The claims first surfaced in the Canard Enchaine weekly, which mixes satire and investigative reporting.
The paper said it had been unable to find anyone who remembered Penelope working in parliament.
Fillon has dismissed the allegations, which are dominating coverage of the campaign, as "mudslinging" and "misogynistic".
In a statement later Wednesday, Fillon said he hoped to speak to investigators "as soon as possible (to) set out the truth", adding that the claims were "baseless".
Fillon's spokesman Thierry Solere confirmed to AFP on Tuesday that Penelope had worked for her husband and said the arrangement was "common" among French MPs.
The candidate will also appear on France's main evening news show on TF1 at 1900 GMT, his camp said.
Hiring family members is not against the rules if the person is genuinely employed, but attention is focused on precisely what work Penelope carried out for a salary of sometimes around 7,000 euros a month.
The Canard Enchaine alleged that Penelope received the money between 1998 and 2012.
It said she also worked for a periodical, Revue des Deux Mondes, owned by a friend of Francois Fillon, between May 2012 and December 2013.
The silver-haired mother-of-five has kept a low profile in Fillon's nearly four-decade political career, telling a newspaper during the rightwing primary campaign last year: "Until now, I have never got involved in my husband's political life."
The couple, who met in their early twenties, live in a chateau near Le Mans in northern France.