Italian police broke up a major Calabrian mafia drug trafficking ring in Rome on Tuesday (January 20), arresting 26 people and seizing more than 600kg of cocaine and hashish.

The group of drug smugglers was led by known members of the 'Ndrangheta, or the Calabrian mob, from the small mountain town of San Luca in the deep south of the country, investigators said.

With Italian businesses struggling to survive six years of on-and-off recession, mafia groups have found fertile ground to launder their criminal proceeds in Rome and other parts of Italy not normally associated with organised crime.

Over the past two decades, police and prosecutors have dealt severe blows to the Sicilian Mafia, which had been the country's most powerful criminal group for decades.

On top of the 600kg seized, police said they documented the trafficking of another 1,500 kilos of cocaine and hashish.

To extend its reach over the city's drug market, the group formed a hit squad to shoot dead a rival mob boss two years ago, police said.

When police tracked down the alleged killers last year, one of them became a witness for the state and provided information vital to Tuesday's arrests, Prestipino said.

The group had logistical bases in Genoa, Milan and Turin, and kept in direct contact via the Internet and through its own emissaries with the most violent Colombian cocaine cartels, Finance Police Commander Cosimo Di Gesu told Reuters.

Of the 31 people sought for arrest, police have tracked down 30, with four taken into custody in Spain.