French National Front leader Marine Le Pen. File picture: Michel Spingler/AP

Paris - The French judiciary have begun their investigation into National Front leader Marine Le Pen over allegations that she had illegally used EU funds to pay aides who were in fact working for her party, legal sources said on Friday.

Her lawyer, Rodolphe Bosselut, said his client would appeal against the charges.

The European Parliament is seeking a repayment of 340,000 euros (380,000 dollars) of misused funds from Le Pen, who, they allege, claimed back salaries from the European Parliament between 2009 and 2016 for two supposed aides who were actually working for her party.

Le Pen, who remains party leader despite calls for her to resign following this year's failed presidential election campaign, has twice denied summonses from judges and police regarding the case.

She had invoked parliamentary immunity as a member of the European Parliament during her presidential and parliamentary campaigns but had pledged to cooperate with the investigation once the campaigns were over.

The French judiciary has already requested that the European Parliament lift Le Pen's immunity.

In February, Le Pen's chief of staff Catherine Griset was charged with breach of trust in the investigation. Le Pen has consistently denied the allegations against herself, saying that they were the work of her political opponents.

Bosselut told the AFP news agency that, in his opinion, the charges contravene separation of powers.