Four men went on trial on Thursday over a 2018 Christmas market attack in France's eastern city of Strasbourg where a radical Islamist killed five people before being shot dead by police after a 48-hour manhunt.

The traditional Christmas market was in full swing on December 11 when Cherif Chekatt -- a convicted criminal featured on a list of possible extremist security risks --  opened fire on revellers, shouting "Allahu Akbar" ("God is Greatest" in Arabic).

The four men on trial in Paris are accused of crimes ranging from terrorism to helping supply weapons, including the 19th-century revolver Chekatt used in the attack.

The trial opened at the Paris court with the suspects confirming their names.

One of them, Audrey Mondjehi, faces the maximum penalty of life in prison if convicted of terrorism. The others risk 10 years imprisonment.

The trial, due to last until early April, is the latest legal process over the Islamist attacks that have hit France since 2015.

In December 2022, a Paris court convicted all eight suspects in the trial over a 2016 truck attack in the Mediterranean city of Nice, which left 86 dead.

In the highest-profile case, 20 defendants were convicted in June 2022 over their roles in the November 2015 attack in the French capital, when 130 people were killed.

The Islamic State group claimed the Strasbourg attack, but the then-French interior minister Christophe Castaner said it was taking credit for an attack it hadn't planned.

However, a video pledging allegiance to the group was found at the assailant's home.

– 'Radical convictions'–

Of the accused only Mondjehi, 42, was charged with terrorism, while the three others -- all in their 30s -- face criminal conspiracy charges for their role in supplying weapons.

A fifth defendant, in his mid-80s, may be tried at a later date after a medical examination found his health was not compatible with taking part in the current long trial.

Mondjehi, a former cellmate of the assailant, "could not have been unaware of, or may have even shared, all or part of Cherif Chekatt's radical convictions", according to the indictment.

But his lawyer said he was concerned Mondjehi could be used as a scapegoat in Chekatt's absence.

"Audrey Mondjehi should not be an outlet for the grief of the victims and should not be condemned because Cherif Chekatt is not there," said Michael Wacquez ahead of the trial.

According to the investigation, there was no evidence of the other suspects having been aware of Chekatt's plans.

– 'Turn a page'–

Although Chekatt cannot now be brought to justice, survivors and relatives of victims said the trial was still crucial.

The attack "turned my whole life upside down", said Mostafa Salhane, a 53-year-old former taxi driver who spent 15 terrifying minutes with Chekatt who climbed into his cab with a gun in his hand as he fled the scene.

A lawyer representing some of the families, Arnaud Friederich, said the trial was a "key moment" for his clients. "There will be a before and an after," he said.

Claude Lienhard, a lawyer for several dozen people, said there was a perception the investigation has been dragging on.

"There's a fear that this will be a low-cost trial compared with other terror trials, as many feel they have been forgotten."

Audrey Wagner, who saw Chekatt wound one of her friends, said she expected proceedings to be "distressing" but important to "turn the page".

Jean-Yves Bruckman, a now-retired firefighter who aided one of the victims said he needed answers "to heal".

"One question keeps coming back to me: how can you kill someone like that?"