Paris: Four men suspected of supplying one of the gunmen behind the Paris attacks with weapons and vehicles were brought before an anti-terror judge on Tuesday, the first to face possible charges over the shootings that shook France to its core.
The jihadist attacks put Europe on high alert and a wave of police raids, investigations and extraditions have taken place across the jittery continent.
Both Paris and the EU are on Wednesday due to unveil details of anti-terrorism measures after the worst attack on French soil in decades that left 17 people dead.
The three gunmen who carried out coordinated attacks from January 7-9 were killed in dramatic police sieges, and prosecutors are now hoping to pin down those who assisted them.
Prosecutors called Tuesday for four 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.
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.
A Muslim employee in 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 had signed a petition calling for France to naturalise Lassana Bathily, 24, from Mali.The attacks prompted a flurry of police activity across Europe.
In Germany some 200 police carried out raids on 13 apartments in Berlin and other locations to find evidence against two men arrested last week for allegedly backing jihadist violence in Syria.
This followed raids in Belgium last week that foiled potential attacks against police officers, and led to arrests in several European countries.
Greece on Tuesday ordered the extradition of a 33-year-old Algerian man with suspected links to the jihadist cell dismantled in Belgium.
The suspected mastermind of the plot, Abdelhamid Abaaoud, a 27-year-old Belgian of Moroccan descent, remains at large.
And in Bulgaria, a court ruled that a Frenchman who knew two of the Paris attackers should be returned to his home country.
France had issued an arrest warrant for Muslim convert Fritz-Joly Joachin, 29, who denies being an extremist but was detained after trying to cross from Bulgaria into Turkey before the attacks.
In southern France, five Russians from Chechnya were arrested on Tuesday 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.On high alert after the attacks, France has promised measures to boost security forces, which Prime Minister Manuel Valls will 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.
Interior Minister Bernard Cazeneuve has said intelligence services could receive additional funding while security forces could get more powerful weapons and improved equipment.
Meanwhile European Union commissioners will meet to discuss their counterterrorism strategy across the 28-nation bloc.
"They will discuss subjects including passenger name records and data retention, the functioning of the Schengen area and cooperation between security services," Commission spokesman Margaritis Schinas told a briefing on Tuesday.
Many EU states have pushed for a US-style database of air travellers` details on the grounds that it would help track Islamist suspects, but the European Parliament has so far blocked the scheme saying it would breach civil liberties.
Some European nations have also been pushing for a tightening of the Schengen visa-free zone.The fallout from the attacks has led to massive protests in Muslim countries, furious after Charlie Hebdo magazine responded to the killing of its staff by publishing a new cartoon of the Prophet Mohammed.
Banned by Islam, the depiction of the prophet was taken as a searing insult to Muslims who burned French flags, and threatened the country in protests which have taken place in Chechnya, Afghanistan, Gaza, Iran and Pakistan.
In Niger protests turned deadly as 10 people died and dozens of churches were torched.
Seeking to douse the anger, Valls said "`Je suis Charlie` is not our only message to the world.
"France carries freedom of expression everywhere, but it also defends other values it holds dear: peace, respect for beliefs, dialogue between religions," he said.
The attacks have forced France to face up to its failure to integrate poorer, migrant families, with Valls admitting on Tuesday that the country was plagued by "social and ethnic apartheid".