As specified, the man was detained in the commune of Sparanise in the Italian region of Campania.
A warrant for his arrest was issued by a French court.
According to ANSA, the suspect supplied the terrorist with weapons.
On July 4, 2016, a terrorist truck rammed people who had gathered on the Promenade des Anglais in Nice to watch the Bastille Day fireworks, killing 86 people.
The terrorist attack was committed by a 31-year-old resident of Nice, Tunisian origin, Mohamed Lahuayej Buhlel.