PARIS (AFP) - Five women went on trial on Monday (Sept 23) over an alleged plot to detonate a car bomb in front of Paris' Notre-Dame cathedral as France battles a wave of Islamist attacks that have killed over 250 people since 2015.

It is the first time women have appeared on charges of radical Islamic terrorism in an assize court, which handles the most serious crimes in France.

Four of the women risk up to life in prison, and the fifth faces a 30-year sentence for the September 2016 plot involving the mediaeval cathedral, which in April this year was ravaged by an accidental fire.

A sixth woman is also being tried for not alerting the authorities to the planned attack.

The women were arrested after an empty Peugeot 607 sedan was found parked near the bustling square outside Notre-Dame. A bar employee had noticed a gas cylinder in the back seat and alerted the police.

That cylinder was found to be empty but five full cylinders were discovered in the car boot.

Prosecutors say that on the night of Sept 3-4, 2016, Ines Madani and Ornella Gilligmann parked the car after sending a video claiming responsibility for the planned attack to Rachid Kassim, a notorious French member of the Islamic State in Iraq and Syria.

Kassim is also suspected of directing the brutal murder of a police couple outside their home in June 2016, a killing that was broadcast live on Facebook, and another in which an elderly priest's throat was cut.

Kassim is believed to have been killed in a coalition air strike near the Iraqi city of Mosul in February 2017.

For Mr Jean-Charles Brisard of the Centre for the Analysis of Terrorism, the foiled plot marked a tipping point: "It's the moment when people realised the role of women" in the terrorist attacks on French soil.

'WRONG CHOICE OF FUEL'

Madani, now 22, and Gilligmann, a 32-year-old mother of three, had doused the car with diesel fuel and tried to set it alight with a cigarette, but failed because the fuel is not easily flammable.

"Only the wrong choice of fuel... caused this attempt to fail," investigating magistrates said.

Gilligmann was arrested on Sept 6 in southern France while trying to flee, and Madani holed up in an apartment in the Paris suburb of Essonne that belonged to Amel Sakaou, who is also on trial.

She was guided by Samia Chalel, who served as an intermediary between Madani and Kassim.

They were soon joined by Sarah Hervouet, who was also communicating with Kassim via the encrypted Telegram messaging app.

They were arrested a few days later after trying to leave the apartment armed with kitchen knives. Hervouet stabbed one officer in the shoulder, while Madani was shot in the leg.

"She's obviously intimidated," said defence lawyer Laurent Pasquet-Marinacce, as the trial got underway.

"It is very daunting to be judged by a Court of Assize but she is quite confident because she believes in the possibility of a fair and not excessive trial."

Ms Marinacce rejected allegations her client orchestrated the plot, which she said was a "collective emulation".

"The real people in charge are the men in Syria who were pulling the strings," she said.

Madani was jailed for eight years last April for trying to recruit hardline fighters ahead of the plot to fight in Syria or carry out attacks in France and Belgium.

She used pseudonyms and modified her voice to appear as a man - prosecutors say it was only after the failed attack that Gilligmann learnt that a man she had fallen in love with on the Internet was in fact Madani.

Mr Guillaume Denoix de Saint-Marc, spokesman and founder of the French Association of Victims of Terrorism, which is a civil party in the trial, said it showed that women could also be radicalised.

"We really have to follow this very closely to better understand them, to judge them, to obtain justice, because they really wanted to kill," he said.

The trial is expected to last until Oct 11.