“The person who carried out the operation in Nice, France, to run down people was one of the soldiers of Islamic State,” the Amaq news agency affiliated with the militant Islamist group said on its Telegram account.
“He carried out the operation in response to calls to target nationals of states that are part of the coalition fighting Islamic State.”
French authorities have yet to produce any evidence that the 31 year-old Tunisian killer, shot dead by police in the attack, had turned to radical Islam. Nevertheless, Interior Minister Bernard Cazeneuve said after the claim that a transformation may have happened fast.
“It seems that he was radicalized very quickly — in any case these are the elements that have come up from the testimony of the people around him,” Cazeneuve told reporters.
Speaking from his home town in Tunisia, Bouhlel’s sister told Reuters he had been having psychological problems when he left for France in 2005.
Other relatives and friends interviewed in Nice doubted he had militant Islamist leanings.
Saturday’s arrests, which came on top of two others since the killing, including the attacker’s wife, concerned his “close entourage”, police sources said.
Bouhlel had been in France for 10 years and lived locally.
He drove at the crowd in the Riviera city on Thursday night, zig-zagging along the seafront Promenade des Anglais for two kilometers as a fireworks display marking the French national day ended, until police eventually shot him dead.
The attack plunged France into new grief and fear just eight months after gunmen killed 130 people in Paris. Assaults in January 2015 on satirical newspaper Charlie Hebdo and a Jewish supermarket were also claimed by Islamic State, which controls swathes of Iraq and Syria but is now under military pressure from forces opposed to it.