PARIS (AFP) - French investigators on Monday quizzed presidential hopeful Francois Fillon and his Welsh-born wife Penelope over allegations that Penelope received 500,000 euros ($760,229) for a fictitious job as a parliamentary aide, legal sources said.

The couple, who are the target of an embezzlement probe, were also questioned over payments Penelope received from a literary review owned by a billionaire friend of her husband.

The Canard Enchaine investigative newspaper revealed last week that former prime minister Fillon had paid his wife for years from public money available to him as an MP for parliamentary aides.

While employing family members is not illegal, the paper said it could find no proof that she did any work in return for the payments.

Fillon has vehemently denied any wrongdoing by him or his wife, insisting that when he was an MP in Paris his wife did a lot of constituency work.

The scandal has damaged the conservative politician, whom polls had shown leading the race on an image of integrity and promises to slash public spending.

Fillon has claimed he is the victim of a political dirty tricks campaign.

Penelope, a mother of five, has always styled herself as low-key political wife who preferred to remain at the couple's country home rather than in Paris. She has not spoken publicly on the affair.