Four men suspected of providing logistical support to one of the Paris gunmen have been charged with associating with terrorism — the first charges handed out for the mayhem that left 20 people dead, the Paris prosecutor said Wednesday.

Outlining a web of phone calls, shared keys and prison friendships, Paris Prosecutor Francois Molins said the four men — all in their 20s, all arrested in the Paris region — were handed preliminary charges overnight. They will be jailed until a further investigation.

The prosecutor did not give the suspects' full identities, naming them only as Willy P., Christophe R., Tonino G. and Mickael A.

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Three of the men are suspected of buying weapons — and one kept them at his house — for Amedy Coulibaly, who shot a policewoman to death Jan. 8 on the outskirts of Paris and then a day later killed four hostages at a kosher supermarket in the French capital before being killed in a police raid.

Three of the four men charged had criminal records; at least one met Coulibaly in prison, Molins said. Coulibaly himself had met Cherif Kouachi, one of the two brothers who killed 12 people at the Paris newspaper Charlie Hebdo, in prison.

The lawyer for one of those charged said his client was unaware of any terrorist plot and was afraid of Coulibaly. Lawyer Fabrice Delinde told BFM television said the gunman "terrorized my client" and intimidated him into helping.

Molins said three of the men are believed to have procured weapons and tactical material for Coulibaly, but are not charged with complicity in the attacks.

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The DNA of Mickael A. was found on a revolver in Coulibaly's apartment and on a glove the gunman wore in the supermarket. Molins also said Mickael A. had 18 phone contacts with Coulibaly on Jan. 6.

Molins said that authorities in France are working with other countries to search for other possible accomplices. They are especially trying to uncover who was responsible for the posthumous video of Coulibaly, which was edited and released days after he and brothers Said and Cherif Kouachi died in standoffs with police.

In the video, Coulibaly pledges allegiance to the Islamic State group and details how the attacks were co-ordinated by the three men.

Prime Minister Manuel Valls is expected to present new security measures Wednesday that will include efforts to increase intelligence-gathering against jihadis and other radicals and block their activities on the Internet. The measures will also prevent them from collaborating inside prisons or travelling abroad to fight.

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France has repeatedly strengthened its counterterrorism laws over the years, most recently with a new measure passed in November centring on preventing French extremists from joining fighters abroad. One measure — which is expected to be activated in the coming weeks — would allow administrative authorities to ask Internet service providers to block sites that glorify terrorism.

Meanwhile, France's cyber-vulnerabilities have come into view. Interior Minister Bernard Cazeneuve said that Islamic extremist-hackers have claimed responsibility for more than 1,300 attacks on French civilian and military Web sites since the Paris terror attacks. The low-grade vandalism, like altering Web sites or home pages, was aimed to show sympathy with the terrorists.

Overnight Wednesday, the Twitter feed of Le Monde newspaper was hacked by the Syrian Electronic Army, a group that aligns itself with Syrian President Bashar Assad.