The Abergavenny-born wife of French presidential candidate Francois Fillon has been placed under formal investigation over allegations surrounding well-paid parliamentary jobs that investigators suspect she never performed.

Sixty-one year old Penelope Fillon is being prosecuted for embezzlement, misappropriation of public funds and aggravated fraud after spending Tuesday being questioned by magistrates. The announcement that she had been mise en examen – the equivalent in French law of being charged or arraigned – came after several hours of questioning by the French financial prosecutor.

Her husband was placed under formal investigation earlier this month, accused of paying hundreds of thousands of euros to his family for work they did not do. The centre-right contender and his wife deny any wrongdoing and while Mr Fillon claims the allegations are part of a ‘smear campaign’ designed to torpedo his presidential bid they have deeply damaged his chances in the two-round election on April 23 and May 7.

He is accused of paying hundreds of thousands of euros to his wife and children for work they did not do and paying his wife public money for work as his parliamentary assistant. Opponents claim that the work she did was trivial or non-existent, she did not have a parliamentary pass and say that few people were aware she was even a member of his staff

There are also questions about a job Mrs Fillon had at a literary magazine owned by a billionaire friend of the couple, for which she allegedly did little or no actual work.

Mr Fillon is also being investigated over payments to his two children, Marie and Charles when he said his children were paid as lawyers for specific tasks, despite the fact that neither was a qualified lawyer at the time.

In all, Mr Fillon is suspected of diverting public funds, complicity in misappropriating funds, receiving the funds and not declaring assets fully.

Mr Fillon and his wife have always vehemently denied the accusations and Mr Fillon has accused the government of trying to discredit him, attacked the legal system and lashed out at the media.

Under French law members of parliament are entitled to employ relatives if the jobs are real and work is done but this week the French financial prosecutor decided after a preliminary investigation that there was enough doubt over whether Penelope Fillon’s job was ‘fictitious’ to continue the inquiry.

The official accusations against her are complicity and concealment of embezzlement of public funds, complicity and concealment of abuse of social goods and complicity and concealment of fraud.

Ironically should Mr Fillon become President in May, he would enjoy presidential immunity from prosecution during his time in office, while his wife could find herself in court although current opinion polls suggest this is now unlikely.