A 47-year-old man has been taken into custody on suspicion of having been in contact with the perpetrator of Thursday's deadly knife attack in Nice, a judicial source said.
On Thursday, a knife-wielding attacker beheaded a woman and killed two other people in a church in the French city before being shot by police and taken away.
The source said the 47-year-old suspected of having been in contact with the attacker had been detained late on Thursday evening, confirming an earlier report on BFM TV.
France's chief anti-terrorist prosecutor Jean-Francois Ricard said the man suspected of carrying out the attack was a Tunisian, born in 1999, who had arrived in Europe on September 20 in Lampedusa, the Italian island off Tunisia that is a major landing point for migrants from Africa.
A Tunisian security source and a French police source named the suspected attacker as Brahim Aouissaoui.
Ricard said the suspected attacker had entered the city by train early on Thursday.