The man who killed 84 people in Nice had planned his attack in the days prior to Bastille Day and had recently developed an interest in radical Islam, the Paris prosecutor said on Monday.

"If there are no elements in the investigation to suggest at this stage an allegiance to Islamic State nor links with individuals from the group ... he (Mohamed Lahouaiej Bouhlel) showed a certain recent interest for radical jihadist movements," Francois Molins said.

Molins said that Bouhlel had in the days and two weeks prior to the July 14 attack sought to raise money through a bank loan, which was denied, a cash withdrawal and the sale of his car.

He paid 1,600 euros ($1,772) on July 4 to hire the truck used to ram into dozens of people on Nice's Promenade des Anglais and in the immediate days prior to the attack, Bouhlel was caught twice on surveillance cameras rehearsing the journey that he would take on July 14, Molins said.

The prosecutor said Bouhlel had told people close to him that he had been growing his beard for religious reasons and that he could not understand why Islamic State could not have its own territory.

He said photos and videos linked to radical Islam and Islamic State had been found on his telephone and computer.