Luxembourg (AFP) - French far-right leader Marine Le Pen must repay nearly 300,000 euros to the European Parliament for funds paid incorrectly to an assistant, a top EU court ruled on Tuesday.

The General Court of the European Union, the bloc's second-highest tribunal, rejected a bid by Le Pen to overturn a ruling that she had wrongly used parliamentary funds to pay an aide who was based at her party's headquarters in Paris.

The Luxembourg-based court said in a statement that it "confirms the decision of the European Parliament to recover from Marine Le Pen MEP almost 300,000 euros ($347,000) for the employment of a parliamentary assistant, on the ground that she did not prove the effectiveness of that assistant’s work".

Le Pen, who lost the 2016 French presidential election in a run-off with Emmanuel Macron, provided no evidence "of any activity whatsoever on the part of the parliamentary assistant that comes under parliamentary assistance, which she moreover acknowledged during the hearing," the court said.

Le Pen, who served as an MEP from 2009 to 2017, swiftly announced her intention to take the case to the Court of Justice of the European Union, the bloc's highest court.

"This ruling is based not on the substance of the case but on a procedural aspect. We are going to appeal against this decision," she told AFP.

Le Pen's National Rally party -- known until a recent name change as the National Front -- criticised the court's ruling.

"When you don't submit evidence the General Court says there was no parliamentary work. When you submit evidence it says it's in the wrong form. Then when you submit the evidence in the right form, it says it's too late," the party said in a statement.

In December 2016, the parliament ruled that 298,500 euros had been "unduly" paid to Le Pen over a five-year period for parliamentary assistance provided by her aide Catherine Griset, who was based in Paris and not at parliament, which meets in both Brussels and Strasbourg, eastern France.

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The parliament began withholding part of Le Pen's allowances as an MEP to recover the money -- a move that she unsuccessfully challenged in the EU court last year.

A source at the European Parliament told AFP that it managed to recover around 60,000 euros from Le Pen before she quit the assembly in 2017.

Le Pen is not the only member of the former National Front to run foul of rules on payments to parliamentary aides.

Her father Jean-Marie Le Pen, the founder of the National Front, was ordered to repay 320,000 euros in 2016, while parliament has demanded a total of nearly 400,000 from three other MEPs.