A group of women are accused of attempting to blow up Notre-Dame using a car bomb - which only failed after the wrong fuel was used, a court has heard.
Five women went on trial Monday over an alleged plot to detonate a car bomb in front of the cathedral in Paris three years ago.
It is the first high-profile case involving women accused of wanting to carry out a terror attack in France.
Two of the women were arrested after an empty Peugeot 607 sedan was found parked near the bustling square outside Notre-Dame, where a bar employee noticed a gas cylinder in the back seat and alerted the police.
Police attended and discovered the cylinder was empty but then found five full cylinders in the car boot.
Prosecutors say in 2016 on the night of September 3-4, Ines Madani, 22, and Ornella Gilligmann, 32, parked the car after sending a video claiming responsibility for the planned attack to Rachid Kassim, a notorious French member of ISIS.
They claim the pair 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.
Ms Gilligmann was arrested in southern France while trying to flee, and Ms Madani was found in an apartment in the Paris suburb of Essonne that belonged to Amel Sakaou, who is also on trial.
Another woman Samia Chalel is accused of serving as an intermediary between Ms Madani and Kassim.
A fifth woman, Sarah Hervouet, is accused of communicating with Kassim via the encrypted Telegram messaging app.
The group were arrested a few days later after trying to leave the apartment armed with kitchen knives. Ms Hervouet allegedly stabed stabbed one officer in the shoulder, while Ms Madani was shot in the leg.
The failed attack is thought to have been piloted by Kassim, mainly via the Telegram app.
Kassim, who is being tried in absentia, is also suspected of directing the 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.
The trial is expected to last until October 11.
