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 says.

The Tunisian man who carried out the lorry attack in the French city of Nice researched his route in the days beforehand, French media reports say.

A lorry racing into a crowd after Bastille Day celebrations in the French city of Nice kills at least 84 people, injuring at least 18 more.