PARIS • France's National Assembly has lifted the immunity from prosecution of far-right leader Marine Le Pen for tweeting pictures of atrocities by the Islamic State in Iraq and Syria (ISIS) group.

The decision was taken on Wednesday by a cross-party committee in charge of the internal functioning of the assembly, after a request from the authorities to lift Ms Le Pen's parliamentary immunity.

The leader of the National Front (FN), who ran a failed bid for president this year, in 2015 tweeted three pictures of ISIS violence.

One showed the body of Mr James Foley, an American journalist beheaded by the Sunni extremists. The others showed a man in an orange jumpsuit being driven over by a tank and a man being burned alive in a cage.

"Daesh is this!" Ms Le Pen wrote in a caption, using an Arabic acronym for ISIS.

Circulating "violent messages that incite terrorism or pornography or seriously harm human dignity", and that can be viewed by a minor, is a crime punishable by up to three years' jail and a fine of €75,000 (S$119,000) in France.

Following a request from Mr Foley's family, Ms Le Pen eventually deleted the image of the American, saying she had been unaware of his identity.

In September, Parliament also lifted the immunity of another FN MP, Mr Gilbert Collard, over similar tweets containing ISIS images.

Ms Le Pen, a trained lawyer, slammed the Wednesday move as a "lowly, purely political decision" that violated her freedom of expression. "It's better to be a jihadist returning from Syria than an MP condemning the ignominies of ISIS," she told Agence France-Presse, suggesting France was softer on ISIS members than their opponents.

The authorities began probing the tweets in December 2015 but could not press charges while Ms Le Pen had protection from prosecution. At the time she was a member of the European Parliament.

That assembly voted in March to lift her immunity but three months later, she won it back after being elected to the French Parliament for the first time.

Wednesday's decision of the 22-member assembly committee is the latest blow to the 49-year-old politician, who has appeared adrift since her defeat at the hands of Mr Emmanuel Macron in May's presidential run-off.

Ms Le Pen lost to Mr Macron with a lower-than-expected 33.9 per cent to his 66.1 per cent of the vote after floundering badly in a final TV debate between the pair.

The FN also fared poorly in June parliamentary elections, taking just eight seats out of 577.

AGENCE FRANCE-PRESSE