The Islamic State Group said Saturday in a statement that the attacker was "one of the soldiers of Islamic State," whilst French police arrested three people in Nice in connection to the truck attack that killed at least 84 people on Bastille Day, according to Reuters.
"He carried out the operation in response to calls to target nationals of states that are part of the coalition fighting Islamic State," news agency Amaq said via its Telegram account.
French authorites were investigating the claim and were still trying to determine whether the 31-year old Tunisian driver of the vehicle had acted alone or with accomplices, and whether his motives were connected to radical Islam.
He was not known to French intellegence sources for radicalization.
The police arrests concerned the attacker's "close entourage", including the attacker's wife and were made in two different areas of Nice.
A Reuters reporter saw about 40 elite police raid a small apartment at Rue Miollis, north of the central station, where one individual was arrested.
The driver, Mohamed Lahouaiej Bouhlel, was shot dead by officers at the scene. He was known to police for petty crimes but was not on a watch list of suspected militants. He had one criminal conviction for road rage, having been sentenced to probation three months ago for throwing a wooden pallet at another driver.
French officials had not disclosed any direct evidence linking Bouhlel with jihadism.
French Interior Minister Bernard Cazeneuve, asked on Friday if he could confirm the attacker's motives were linked to jihadism, said: "No. ... We have an individual who was not known to intelligence services."