A man covered with a towel is apprehended by French police as the investigation continues two days after an attack by the driver of a heavy truck who ran into a crowd on Bastille Day killing scores and injuring as many on the Promenade des Anglais, in Nice, France, July 16,...
"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 that Mohamed Lahouaiej Bouhlel may have undergone a rapid change.

"It seems that he was radicalised 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.

July 16's arrests concerned his "close entourage", police sources said. Two other people, including the attacker's wife, had already been detained.

Bouhlel had been in France for 10 years and lived locally.

He drove at the crowd in the Riviera city on July 14 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 Health Ministry said 121 people remained in hospital, including 30 children. Twenty-six individuals were still in intensive care.

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.

A state of emergency in place since the Paris killings last November is to be extended for another three months. On July 16, Cazeneuve called on "patriotic citizens" to become reservists to help relieve exhausted security forces.

Bouhlel 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.

Edwin Bakker, Professor at the Centre for Terrorism and Counterterrorism at the University of Leiden in the Netherlands, said Islamic State's claim did not necessarily point to any formal link.

"Islamic State called for such (individual) attacks to be carried out back in 2014. They are also using the public perception that an attack like this seems to fit Islamic State.

"Investigators still have not discovered a direct link between Islamic State and the attacker, so it is a cheap claim," he said.