Prosecutors have expanded an embezzlement probe into the Monmouthshire born wife of a French presidential candidate.

National financial prosecutors have been investigating Penelope Fillon’s work as a parliamentary aide to her husband, seeking to determine whether there are grounds to suspect embezzlement and misappropriation of public funds.

A person close to the investigation told the Associated Press that prosecutors have extended the probe to also cover the couple’s daughter Marie and son Charles.

Allegations that Mr Fillon’s family used his political connections to enrich themselves with cushy parliamentary jobs have been particularly damaging for the former prime minister’s image as an upstanding Catholic family man and country gentleman untainted by the long history of sleaze in French politics.

The contrast between Mr Fillon’s words and his supposed actions sting because he has promised to slash public-sector jobs and make the French work harder and longer.

His nose-diving prospects of winning France’s two-round presidential election in April and May have thrown open the race that had been expected to be between him and far-right National Front leader Marine Le Pen.

The Canard Enchaine weekly has reported that Mr Fillon hired his children as parliamentary aides when he was a French senator between 2005 and 2007, and they earned €84,000 (£72,000) in total.

Mr Fillon has confirmed he paid two of his children, “who were lawyers”, for “specific assignments” when he was a senator. The children were in law school when they worked for their father, French media have reported.

According to Le Canard Enchaine, they drew salaries not for assignments, but for two full-time jobs. French politicians are allowed to hire family members as aides as long as they actually do the jobs for which they are paid.

Mr Fillon insists that Penelope’s work for him was genuine.

Piling on the pressure on Mr Fillon, France Televisions said it would screen extracts on Thursday evening from an interview with Mrs Fillon in 2007, when her husband was prime minister, in which she said she had never worked as his assistant.

It would contradict the couple’s defence in recent days that she was legitimately employed as his parliamentary aide.Mr Fillon and his wife were separately questioned by investigators for five hours on Monday and the Canard Enchaine reported on Wednesday that she made €830,000 (£713,000) over 15 years.