"Organised crime is moving abroad, globalising," Giuseppe Governale, the head of Italy's anti-mafia investigative unit DIA, said during a meeting with the foreign press in Rome.
Governale said that although the notorious Sicilian Cosa Nostra has "always been present in the United States, Canada and Australia", the influence of the Calabrian mob, known as the 'Ndrangheta, was "underestimated".
"The 'Ndrangheta ... is an extraordinarily powerful organisation," Governale warned.
He said criminal organisations have contacts all over the world in countries where they operate, but insisted 'Ndrangheta "tends to replicate abroad the structures it has established in Calabria".
In Brussels, for example, "they don't buy just buildings but entire neighbourhoods".
Governale added that Cosa Nostra, a notoriously ruthless criminal organisation responsible for perpetrating deadly attacks in the past, was today "in great organisational difficulty after suffering substantial blows".
Most of the mob's upper ranks have been arrested, with the exception of kingpin Matteo Messina Denaro.
Fugitive Denaro has been on the run since 1993, with police closing in on his closest aides, but Governale said he was no longer considered the mob's supreme leader.
He warned, however, that the death in prison in November 2017 of Cosa Nostra's former kingpin, Totò Riina, could prompt the organisation to name a new head.
Governale said Cosa Nostra has been weakened, but "unfortunately, the conditions linked to its environment and that allow its development still exist".
"The mafia will be defeated by an army of schoolteachers," he said, referencing a line from the Italian poet and writer Gesualdo Bufalino, who died in 1996.