Prosecutors in France have placed the far-right leader Marine Le Pen under formal investigation as part of a probe into the alleged misuse of European Union funds to pay parliamentary assistants.
The 48 year old head of the National Front is being investigated for breach of trust and has denied any wrongdoing.
She says the case is politically motivated.
In a statement, her lawyer said she would launch an appeal.
Under French law, being put under formal investigation means there is “serious or consistent evidence” that points to probable involvement in a crime.
It is a step towards a trial, though investigations can be dropped without proceeding to court.
The case relates to an amount of about US$5.71 million.
The European Parliament believes the money went to National Front employees working for the party in France rather than those working for its lawmakers in Brussels.
She is one of 17 of her party’s lawmakers, including her father Jean-Marie Le Pen from whom she is estranged, under investigation over the alleged salary irregularities.
The others also deny any wrongdoing.
It was announced Le Pen had been placed under formal investigation after she appeared before judges on Friday.
She had been summoned previously, but refused to go during her campaign bid for the French presidency.
The anti-EU nationalist beat the candidates of the traditional right and left to secure a spot in May’s presidential run-off against the pro-EU centrist Emmanuel Macron.
But she was soundly beaten by Macron in the second round, by 66.1 to 33.9 percent.
In legislative elections held directly afterwards she won a seat in the northern former coalmining region of Pas-de-Calais.
Le Pen has already had her parliamentary immunity lifted over a separate case from 2015 when she shared graphic pictures of atrocities committed by the Islamic State group on her Twitter account.
Those pictures saw her placed under investigation for the “dissemination of violent images”.