France's National Assembly on Wednesday lifted the immunity from prosecution of far-right leader Marine Le Pen for tweeting pictures of Islamic State group atrocities.

The decision was taken by a cross-party committee in charge of the internal functioning of the assembly, after a request from the authorities to lift Le Pen's parliamentary immunity over a crime that carries up to three years in prison.

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

One showed the body of James Foley, an American journalist beheaded by the Sunni extremists.

Marine Le Pen is now facing charges 'violent messages that incite terrorism or pornography or seriously harm human dignity' and that can be viewed by a minor. If convicted she faces up to three years and a fine of €75,000

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!' Le Pen wrote in a caption, using an Arabic acronym for IS.

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 and a fine of €75,000 in France.

Following a request from Foley's family 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, Gilbert Collard, over similar tweets containing IS images.

Le Pen, a trained lawyer, slammed the move as a 'lowly, purely political decision' which violated her freedom of expression.

Le Pen tweeted a picture showing the body of James Foley (pictured), an American journalist beheaded by the Sunni extremists with the words Daesh is this!', using the Arabic acronym for IS.

Le Pen has been under investigation since 2015 but charges could not be brought until immunity was lifted

'It's better to be a jihadist returning from Syria than an MP condemning the ignominies of IS,' she said, suggesting that France was softer on IS members than their opponents.

The authorities began investigating the tweets in December 2015 but could not press charges while 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 Emmanuel Macron in May's presidential runoff.

After proving a formidable opponent, Le Pen lost to Macron with a lower-than-expected 33.9 percent to his 66.1 percent 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.

Tensions between rival party factions - one led by anti-immigration hardliners, the other by anti-EU nationalists - burst into the open in September with the resignation of Le Pen's right-hand man Florian Philippot.

Philippot was the architect of Le Pen's strategy to detoxify the FN brand as well as her unpopular plan to pull France out of the eurozone.