A prosecutor in Sicily says that an investigation has found "evidence" of contacts between rescue boats run by some humanitarian groups and Libya-based migrant smugglers.

Catania Chief Prosecutor Carmelo Zuccaro was quoted as saying in an interview published Sunday in La Stampa newspaper that the probe has revealed "evidence there's direct contacts between some NGOs and human traffickers in Libya."

Nine nongovernmental organizations have operated rescue boats in the Mediterranean just outside Libya's territorial waters. Rescue operations are ultimately coordinated by the Italian coast guard under maritime rules requiring help be given to distressed boats.

Populist Italian politicians on Sunday demanded to know who's financing the NGOs.

Premier Paolo Gentiloni has praised NGOs' saving lives, but says it's right that prosecutors investigate any contacts.