Five people believed to be linked to the man who killed 84 people in Nice are in police custody, the Paris prosecutor’s office says.
Three arrests were made on Saturday and two on Friday, including the man’s estranged wife, Le Monde reported.
Mohamed Lahouaiej-Bouhlel drove a lorry into crowds marking Bastille Day on the Promenade des Anglais on Thursday before he was shot dead by police.
So-called Islamic State claimed one of its followers carried out the attack.
A news agency linked to the group, Amaq Agency, said: “He did the attack in response to calls to target the citizens of the coalition that is fighting the Islamic State.”