A fake jobs scandal that has engulfed the French presidential candidate Francois Fillon looks set to deepen as prosecutors are poised to open legal proceedings against the former prime minister.

The French weekly, Jounal du Dimanche, has reported that France's financial prosecutor is now considering how to start proceedings against Fillon and his British wife Penelope. The decision by Eliane Houlette follows 17 days of investigation into the work by Fillon's family.

Reuters news agency received no comment from Fillon's campaign staff on the news. The candidate is currently visiting the French island of Reunion in the Indian Ocean.

Fillon had been the establishment favourite to buttress support for the centre against the populism of far-right leader Marine le Pen. However, the Republican candidate, who presented himself as fiscally responsible and transparent, has been overwhelmed by accusations his family were given fake jobs and paid hundreds of thousands of euros in public money.

A poll conducted by Odoxa for France Info on Friday (10 February) has shown seven out of 10 French voters want Fillon to pull out of the race. For a candidate to step down at this point in the campaign would be unprecedented in France.

On Tuesday (7 February), Fillon apologised for employing his family but denied any wrongdoing.

The next day, further information emerged. Le Canard Enchaine which has published a series of stories on Fillon and his family since January alleged his wife was paid €45,000 (£38,000, $48,000) in severance for work she never did.

Penelope Fillon
Penelope Fillon, wife of former French prime minister and winner of the right-wing primaries ahead of France's 2017 presidential elections GEtty

That money was in addition to €830,000 she was paid as a legislative aid. Testimony from a number of former employees in Fillon's office, as well as Penelope's own answers given in previous interviews, have been given as evidence that she never worked for her husband and essentially was paid for a "fake" job.

The couple's two children also reportedly earned €84,000 between them from 2005-2007. As Fillon's popularity has waned, polls suggest he may be eliminated in the first round of voting in April's election, sparking a likely run-off between centrist Emmanuel Macron and Le Pen.