Italian police say they had arrested a 36-year-old Algerian man on suspicion of belonging to the Islamic State group and helping the authors of the November 2015 Paris attacks.
"The investigations have made it possible to ascertain ... the proximity of the suspect to radical jihadist environments, as well as his direct support to the authors of the terrorist attacks at the Bataclan theatre," police in the southern city of Bari said in a statement.
The man, identified by La Repubblica newspaper as Athmane Touami, is alleged to have "guaranteed the availability of forged documents" to the Paris attackers, police said.
Some 130 people were killed and 350 wounded in a night of carnage on 13 November 2015, when Islamist suicide bombers and gunmen attacked various sites in Paris crowded with people, including the Bataclan concert hall, the Stade de France stadium and the bar Le Carillon.
Touami is suspected of being part of an Islamic State cell operating in France and Belgium with his two brothers, according to La Repubblica.
He is alleged to have been in contact with Belgian Abdelhamid Abaaoud, an Islamic State (IS) extremist and mastermind of the Paris attacks as well as Khalid Zerkani, the jihadist preacher in Brussels who recruited scores of young Muslims as jihadist fighters to Syria, it added.
Touami is serving a two-year term in Bari for possession of fake documents and was due to be released in June, police said.
The role of Touami and his brothers Medhi and Lyes was as "forgers at the service of terrorist organisations", able to provide logistical support and other help, according to the detention order cited by La Repubblica.
Living with his brothers in the Molenbeek neighbourhood of Brussels, Touami had contact with Zerkani, now in prison, whom Belgian investigators have described as the country's "biggest recruiter" of jihadist fighters.
The detention order, according to Repubblica, states that Touami also had contact with Abaaoud, considered the coordinator of the Paris attacks who shot indiscriminately at cafe patrons that night, and his accomplice Chakib Akrouh.
Abaaoud and Akrouh were killed in a police raid five days after the attacks.
The order also claims that since 2010, Touami and his brothers also had contact with Amedy Coulibaly and Cherif Kouachi, two of the extremists in the earlier Paris attacks of January 2015, who targeted a Jewish supermarket and the Charlie Hebdo newsroom, respectively.