French police have questioned ten people suspected of providing material assistance in a truck attack on a crowd of people in the southern city of Nice last July which killed 86 people.
A judicial source said on Monday that the suspects being questioned included several people from eastern Europe.
The source noted that police were investigating who may have supplied the attacker with weapons.
"We are talking here about a logistical trail, of people who could have helped in carrying out the attack."
French law enforcement agencies had earlier detained several people in the aftermath of the attacks on suspicion of being part of the attacker's logistics' network.
At least 80 people were killed and over 200 others were injured on July 14 when a truck ran through a crowd of people celebrating the French National Day, commonly known as Bastille Day, in the southern French city of Nice.
The attacker was shot dead by police at the scene.
The attack, carried out by a Tunisian, was claimed by Takfiri Daesh terrorist group, which has been wreaking havoc in Iraq and Syria.
French authorities say they have yet to find evidence that the 31-year-old attacker had had any actual links to the militant group.
France has been in a state of emergency since January last year after a series of high-profile terror attacks began to rattle the country. Officials say over 235 people have been killed with the Daesh Takfiri terrorist group claiming responsibility for the bulk of them.