ROME, July 8 (Xinhua) -- Italy arrested a man and expelled three others on suspicion of terrorism, the authorities announced Saturday.

Anti-terrorism police in the southern city of Bari have arrested a 38-year-old man from Russia's Chechen Republic on suspicion of being a foreign fighter.

"Bari Digos (Anti-terrorism police Bari division) detains 38-year-old linked to Chechnyan ISIS foreign fighters transiting through Italy. Involved in December 2014 Grozny attack," Italian state police tweeted.

Investigators say the suspect was part of a commando that carried out the December 2014 attack on a media building in Grozny.

The suspect went on to fight in the ranks of the Islamic State (IS) group in Syria in 2014-2015, police sources told Italian news agency ANSA.

He is also suspected of indoctrinating two Albanian brothers aged 23 and 26 who lived in the southern city of Potenza, and a 49-year-old Russian woman in Naples.

The three have been deported for security reasons. Investigators said the fighter instigated the woman to commit a suicide bombing.

He has been incarcerated on charges of conspiracy with intent to commit international terrorist acts and instigation to commit crimes.

On July 4, the Italian Interior Ministry announced the deportation of a 22-year-old Tunisian man for national security reasons. The man, whose brother is known to authorities as a foreign fighter, had been expelled from Italy once before, in December 2015, the ministry said in a statement.

Italy's practice of deporting extremist suspects before they commit crimes has been credited with preventing terrorist attacks in the Mediterranean country.