Four men are facing preliminary charges on suspicion of links to a gunman involved in France's deadliest terrorist attacks in decades.

The Paris prosecutor's office said the four, who would be the first to face charges in the case, are suspected of providing logistical support to Amedy Coulibaly.

Coulibaly shot a policewoman to death on the outskirts of Paris and then seized hostages inside a kosher supermarket, killing four before he was killed by police.

It is not clear whether the suspects were involved in plotting the attacks or even aware of Coulibaly's plans.

The Paris prosecutor's office said five others arrested in the investigation were released today without charge.

The four men, all in their 20s, will appear before an investigating judge later today. No other details were immediately available.

No-one has been charged for direct involvement in the attacks which happened between January 7-9 on satirical newspaper Charlie Hebdo, the kosher supermarket and police.

Twenty people were killed, including the three gunmen, who claimed allegiance to al Qaida and the Islamic State (IS) group.

A Malian employee whose quick thinking saved lives at the kosher market will get French citizenship today.

New York mayor Bill de Blasio also visited Paris today and laid a wreath of flowers near the kosher supermarket.