Three people have now been detained for the terror attack inside the Notre Dame basilica in Nice on Thursday, which killed Simone Barreto Silva, 44, Vincent Loquès, 54, and a 70-year-old woman
A third person is under arrest in France in connection with the knife attack in Nice on Thursday, a police source said on Saturday.
A 35-year-old man is understood to have been arrested on Friday.
Brahim Aoussaoui is suspected of beheading a woman and killing two other people in a church in the city of Nice on Thursday and is now in police custody.
Victims Simone Barreto Silva, 44, Vincent Loquès, 54, and a 70-year-old woman were killed inside the Notre Dame basilica in the city.
A second man was arrested in Nice on Thursday night suspected of being an accomplice of killer Aoussaoui.
The 47-year-old is believed to have supplied the suspected terrorist with a mobile phone.