French judges have ordered far-fight politician Marine Le Pen to undergo psychiatric tests as part of a criminal case that could see her imprisoned for up to three years.

Le Pen is facing charges relating to a series of tweets in which she posted ISIS propaganda pictures of victims of torture and executions.

According to a court document, published by Le Pen herself, the judge wants a psychiatrist to assess if she suffers from any mental illness and, if so, if that could have affected her understanding of what she was doing when she posted the tweets.

The expert is also tasked with determining whether her mental health could be a risk to the public.

Marine Le Pen, 50, is facing charges in a court in Paris, relating to a series of tweets in which she posted ISIS propaganda pictures, including the remains of U.S. journalist James Foley

The Paris court today declined to confirm it had ordered the evaluation but said the assessments were a normal part of such probes.

The 50-year-old politician has been charged with 'violent messages that incite terrorism or pornography or seriously harm human dignity, and that can be viewed by minors.'

If found guilty she could be sentenced to up to three years in prison, and receive a fine equivalent to more than £65,000.

Victim: James Foley was kidnapped and murdered by ISIS in 2014

She had used her Twitter account to post Islamic State torture pictures, including ones of the decapitated body of American journalist James Foley.

Journalist Foley was abducted by ISIS in northwestern Syria in November 2012, and beheaded by the terrorist group in August 2014.

Le Pen's tweets infuriated the Foley family, but Le Pen later claimed: 'I am being charged with condemning the horrors of Daesh [ISIS]. In other countries this would have earned a medal'.

The court in the Paris suburb of Nanterre reportedly now wants a psychiatrist to establish whether Le Pen, who came second to Emmanuel Macron in last year's presidential elections, 'is capable of understanding remarks and answering questions.'

This infuriated the leader of the National Rally, formerly known as National Front, who claims the instructions are a plot by the establishment 'to discredit her'.

Le Pen took to Twitter on Thursday, to say: 'I thought I had been through it all: well, no!

'For denouncing the horrors of Daesh using tweets the "justice system" has referred me for a psychiatric assessment.. How far will they go?!"

Publishing the legal order, Le Pen said: 'It's really incredible. This regime is really starting to worry me.'

She then said it was all part government plot to discredit her, even though there is a strict separation of powers between the executive and judiciary in France.

Ms Le Pen added: 'Of course I will not go to this psychiatric assessment and I will wait to see how the judge intends to force me.'