Italy's top organized-crime fighter has warned of a danger that international terrorism could help finance itself through migrant trafficking.

National Anti-mafia Prosecutor Franco Roberti, presenting an annual report on organized crime, told lawmakers in Rome Tuesday that "clandestine immigration and trafficking can feed international terrorism."

He says that scarce cooperation from transit countries and migrants' homelands meant ringleaders of migrant smuggling go unpunished.

Tens of thousands of migrants and refugees, many from Syria, have reached Italy in recent months on cargo ships, fishing boats and other vessels used by smugglers. Many boats sail from Libya.

Last month, Roberti said in an interview that terrorists could finance themselves through human trafficking as well as arms and drug smuggling.