The three were arrested by officers from Italy's anti-terror squad, Digos, on Sunday night after arriving on a Grandi Navi Veloci car ferry from Tunisia, Il Secolo XIX reported on Tuesday.
They were travelling without luggage in three identical Hyundai cars, and images of weapons and war scenes were allegedly found on their mobile phones.
One of the suspects, a 50-year-old, was reportedly travelling on a Swedish passport.
Meanwhile, a judge in Genoa said on Monday that there are “well-founded suspicions” that two brothers arrested at the Ligurian port city’s airport on December 31st belonged to an international terror group.
The men allegedly attempted to travel to London using fake Belgian documents and also had photos of weapons and war scenes on their mobile phones.
Italy has made several arrests over the past month as part of its anti-terror sweep, including a 45-year-old man suspected of smuggling jihadists into the country.
A Syrian man, suspected of being a terrorist linked to the Isis extremist group, was also arrested in Sicily in mid-December after arriving in the port of Pozzallo.
Some 259 people were arrested on terror charges in Italy in 2015, with 67 of them being expelled from the country as a result.
A Moroccan man was deported in late December after saying he would "blow up Rome".