Presidential candidate Francois Fillon continues to reject claims he paid his wife Penelope for a "fake parliamentary job" and swore he would take to court those he claims are behind the revelations.

The alleged fake jobs scandal, which threatens to derail Fillon's presidential campaign, deepened, after his wife Penelope was placed under formal investigation and charged with the concealment of public funds and abuse of social property on 28 March.

Francois Fillon was placed under formal investigation last month after it was revealed that he had paid his wife more than €810,000 (£700,000, $864,000) as his aide and his two children a combined €92,000 to work as parliamentary assistants.

Speaking to France Inter radio on Thursday (6 April), Fillon defended his wife, and insisted he had "all the details to sue" those behind the allegations.

"It's been two-and-a-half months that I have been prevented from carrying out my (electoral) campaign. I have all the details that will allow me, when the time comes, to sue those who did this," the centre-right candidate said.

"I have the dates, the days, the (identities of the) people who disclosed these documents," Fillon said before adding, "when the time has come, I will sue them".

Fillon evoked a media-driven political conspiracy to take him out of the presidential run, and several times accused outgoing President Francois Hollande of being behind the claims.

The Fillons have both maintained their innocence throughout, with Penelope denying that her husband paid her for a "fake parliamentary job".