Police in southern Italy arrested a 22-year-old Somali imam and asylum seeker on Wednesday on suspicion that he was planning an attack in Rome.
The man was detained at a migrant reception center in Campomarino, in the region of Molise, a police statement said.
"We have clear technical evidence about the possibility that he was organizing an attack in Rome," chief prosecutor Armando D'Alterio told reporters, releasing transcripts of wiretaps where the unnamed man discussed possible violence.
"Let's start from Italy, let's go to Rome and start with the station," he was quoted as telling a friend. The simplest route was to "equip oneself and blow oneself up", he said.
Police said he had used his role as an imam to promote the militant groups Islamic State and Somali Islamist group al Shabaab and encourage Muslims to take up jihad, or holy war.
Italian media said police had arrested the man at the so-called "Happy Family" center because they believed he planned to travel to Rome later on Wednesday.
The police statement said the man had tried to recruit other migrants to travel to Syria for training and believed he wanted to do likewise.