Four men suspected of supplying one of the gunmen behind the Paris attacks with weapons and vehicles have appeared in court.

The men stood before an anti-terror judge on Wednesday and are the first to face possible charges over the Paris shootings.

The January 7 to 9 attacks put Europe on high alert and sparked a wave of police raids, investigations and extraditions across the continent.

• ISIL threatens to kill Japan hostages
• How the Paris shootings have divided Europe
• Why we should call Islamic State the name it hates 

Prosecutors on Tuesday called for the men believed to have supplied Islamist gunman Amedy Coulibaly with weapons and vehicles, to remain in detention and be charged with conspiracy to commit terrorist acts.

The suspects awaited the judge’s decision on Wednesday on whether to open preliminary investigations against them.

Coulibaly was behind the murder of four hostages at a Jewish supermarket and the murder of a policewoman, after brothers Said and Cherif Kouachi gunned down 12 people at satirical magazine Charlie Hebdo.

Meanwhile, a Muslim employee at the kosher supermarket, who was hailed as a hero for trying to save customers during the attack in which four people were killed, was given French citizenship on Tuesday.

About 273,000 people signed a petition calling for France to naturalise Lassana Bathily, 24, from Mali.

Bathily has lived in France for the past nine years and applied for citizenship last year.

In other developments, five Russians from Chechnya were arrested in southern France with what police described as a dangerous amount of explosives, although the case was believed to be linked to organised crime and not radical Islam.

The prosecutor said certain “products” had been recovered during their searches, without giving further details.

One of those arrested lived in Beziers, and another “probably” in Montpellier, the prosecutor added.

The addresses of the other three were still being sought.

On high alert after the attacks, France has promised measures to boost security forces, with Prime Minister Manuel Valls expected to unveil on Wednesday.

Last week Valls announced the creation of special files for people linked to terrorism, and said prisoners linked to radical Islam could be isolated in jail, a hotbed for radicalisation.

– with AAP