Italy's top anti-terrorism prosecutor says recent terror arrests in Italy have been aimed at containing individuals who might be preparing to carry out an attack alone.

Federico Cafiero De Raho was quoted by the news agency ANSA on Thursday as saying that the new phase of terrorism deriving from Islamic State militants is worrying "because we no longer have a structure that is directly governed and directed by a center of international terrorism, but we have lone wolves."

Cafiero De Raho said the new threat are individuals who are often self-trained and become affiliated on the internet. He said only extensive monitoring can combat such individuals, adding that recent arrests in Italy aimed at preventing attacks like the one at the Strasbourg Christmas market this week that killed three people.

Earlier Thursday, anti-terrorism agents arrested a Somalian citizen on terrorism-related charges in the southern city of Bari, saying they believed the suspect was planning to leave Italy "imminently." He was held on suspicion of terrorism association and instigation to commit acts of terror, ANSA reported.

Authorities did not name the suspect publicly or reveal details about his alleged actions that led to the arrest.

Bari has been identified as a transit point for extremists. One of the men who opened fire at a Paris concert venue, killing 90 people, traveled between Bari and Greece on a ferry in the months before the Nov. 13, 2015 attack in Paris.