A French legal source said Thursday that the EU Parliament has accused Marine Le Pen of using funds meant for European parliamentary assistants to pay staff for party work in France between 2012 and 2017, while still leader of the far-right National Front (FN).

The allegations, which Le Pen has denied, triggered an investigation in France.

The parliament had initially estimated the amount of the contested salaries to be 1.9 million euros ($2.1 million) but now believes the FN wrongfully spent 4,978,122 euros, the source said, quoting a note to French investigators from the parliament's legal team.

Patrick Maisonneuve, a lawyer for the parliament, confirmed the amount to French news agency AFP.

Read: European Parliament takes first step to lifting Le Pen's immunity over misused funds

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'Fictional' work contracts

The parliament believes 17 FN lawmakers in the European Parliament, including Le Pen, used European money to pay assistants for work outside the assembly. 

Le Pen, specifically, is accused of paying her bodyguard, Thierry Legier, and her chief of staff, Catherine Griset, with EU parliamentary funds. Le Pen is believed to have submitted a "fictional" work contract before the European Parliament presenting Legier as an assistant, while Griset was living near Paris and working on behalf of the FN in France rather than at the European assembly.

Both were questioned by investigators in February, although only Griset was charged with concealment.

Parliamentary immunity to be lifted

The European Parliament on Wednesday formally began the procedure of lifting Le Pen's parliamentary immunity over allegations, enabling prosecutors to investigate the case.

European Parliament President Antonio Tajani told lawmakers in Brussels that the request "has been forwarded to the Legal Affairs Committee of the European Parliament, which is in charge of these issues."

Le Pen, who will go head to head against centrist Emmanuel Macron in the May 7 presidential election, has denounced legal proceedings against her as a "bare-faced lie."

Read: Le Pen vs. Macron - Where they stand

Punishment for separate case

The European Parliament has already sanctioned Le Pen for allegedly misusing nearly 340,000 euros of EU funds during the 2011-2012 legislature.

Since February the far-right nationalist's monthly salary as an MEP has been cut by half to around 3,000 euros and other allowances have been withdrawn. The current investigation aims at establishing whether other sanctions are warranted.

Last month, Le Pen was also stripped of her parliamentary immunity in a separate case, allowing a Paris court to prosecute her for posting images of "Islamic State" (IS) brutality on Twitter in 2015. In France, the offense can carry a penalty of three years in prison and a fine of 75,000 euros ($79,567).