Nice attack: Neighbour of Mohamed Lahouaiej Bouhlel says he was 'frightening'Reuters

The man who killed more than 80 people on Bastille Day in Nice scouted the scene of the massacre twice in the days leading to the attack, local media reported. Mohamed Lahouaiej Bouhlel rammed a lorry into crowds of revellers watching a fireworks display on the French city's seafront on the evening of 14 July.

He drove the vehicle for 2km (1.25 miles) along the Promenade des Anglais, leaving a trail of death behind him, before he was shot dead by police. Security camera footage revealed that on 12 and 13 July he drove his rented truck to what would become the scene of the attack, apparently to survey the area, according to broadcaster Europe 1.

The carnage was claimed by Islamic State (Isis), but detectives are still assessing whether the attacker – a 31-year-old Tunisian who moved to France in 2005 – had concrete links to the group. French Interior Minister Bernard Cazeneuve said Bouhlel would have been radicalised "very quickly" if he was a part of Isis (Daesh).

Meanwhile, the attacker's brother said that, hours before the attack, Bouhlel phoned him and sent a photo of himself smiling among other people celebrating the France's National holiday in Nice.

"He seemed very happy and pleased, he was laughing a lot," Jabeur Bouhlel told Reuters. He didn't provide copy of the photo, the agency said.

On 17 July police hunting for possible accomplices arrested two more people, a man and a woman. The pair's identities were not immediately released. The arrests brought up the number of suspects held in connection with the attack to seven. However, only six remained in custody as police released Bouhlel's estranged wife – the mother of his three children.

At least 84 people were killed and more than 200 wounded in the attack. Some 85 were still receiving treatment in hospital on 17 July, including 18 in life-threatening conditions, according to Health Minister Marisol Touraine. Authorities were so far able to identify only 35 of the deceased, leaving 49 bodies with no name.

Nice bastille day attack
People form a circle around flowers placed on the road in tribute to victims of the truck attack along the Promenade des Anglais on Bastille Day that killed scores and injured as many in NiceReuters