The legal woes of France's presidential candidates

French prosecutors have asked the European parliament to lift the immunity of far-right presidential candidate Marine Le Pen, ratcheting up an investigation over an expenses scandal on the eve of the election.

The move comes just nine days before the first round of a vote upended by revelations that conservative Francois Fillon had his wife on the public payroll for years, for a suspected fake job as a parliamentary aide.

Following is a summary of the cases facing two of the top five contenders:

Francois Fillon

The 63-year-old former premier has been charged with misusing public money in respect of payments totalling 680,000 euros ($725,000) to his wife Penelope over more than 20 years from funds made available to lawmakers for parliamentary assistants.

French MPs are allowed to employ family members but Fillon has failed so far to convince investigators that Penelope -- a low-key figure who had previously claimed to have had little to do with her husband's career -- earned her salary, which exceeded 10,000 euros a month in 2007.

She herself has been charged with complicity in the affair and concealment.

Prosecutors are also looking into whether they forged a document to justify the payments.

Fillon is also being investigated over payments to two of the couple's children from funds for Senate assistants between 2005 and 2007. Fillon said his daughter Marie helped him write a book and that son Charles compiled notes for him. The younger Fillons later transferred part of the funds to their parents, fuelling suspicions that they had not earned the money.

A staunch Catholic who had campaigned as a man of integrity, Fillon has also been charged over payments to Penelope from a magazine owned by a billionaire friend of his, Marc Ladreit de Lacharriere, and for failing to declare an interest-free loan from Ladreit de Lacharriere to a transparency watchdog.

Fillon has since repaid the loan.

Finally, he is being investigated for possible influence peddling over revelations that he accepted gifts of expensive bespoke suits from a lawyer known for his links to African leaders.

Marine Le Pen

Far-right leader Le Pen, 48, also goes into the election with several investigations hanging over her party and her entourage.

The European Parliament accuses the eurosceptic National Front (FN) leader of using funds for parliamentary assistants to pay staff members for party work in France. Two FN members have already been charged with concealment.

Le Pen invoked her immunity as a member of the parliament to duck out of questioning last month. French prosecutors have asked the parliament to lift her immunity so that she can be prosecuted.

The funding of several campaigns of the FN, which regularly complains of being stretched for cash, has also come under scrutiny.

A close friend of Le Pen's, Frederic Chatillon, is accused of illegally funding the FN's campaign in municipal, European and departmental polls in 2014 and 2015.

Chatillon already faces trial, along with two FN officials, over the party's 2012 general election campaign. The three are accused of setting up a scheme to overcharge for campaign expenses that were reimbursed by the state.

Le Pen is also being investigated by French prosecutors for distributing violent images after tweeting pictures of Islamic State atrocities. The European Parliament has already lifted her immunity from prosecution in that case.

Finally, tax authorities are looking into claims that Le Pen and her estranged father, former party leader Jean-Marie Le Pen, failed to declare the full value of family properties.