The Italian navy said Saturday that its Comandanti-class warship the Cigala Fulgosi intercepted the vessel carrying more than 300 people. It was overloaded and starting so sink off the Libyan coast, the Italian navy said.

"Operation underway... many migrants saved. At least 40 dead," the navy said on Twitter, while the "Corriere della Sera" newspaper reported that the dead were found in the hold of the vessel.

Cmdr. Massimo Tozzi, speaking from the ship, said when his men boarded the distressed vessel they found the dead in the hold "immersed in water, fuel and human excrement."

Asked by RaiNews24 how the migrants died, Tozzi said "it appears to be from inhaling exhaust fumes."

The naval officer said the survivors included three children and 45 women, some of whom "were crying for their husbands (and) their children who died in the crossing."

An exact tally of casualties is still ongoing.

"They are still counting the victims," Interior Minister Angelino Alfano told reporters after giving the figure of 320 rescued.

The latest tragedy at sea is just the latest in a wave of sea disasters as thousands of migrants - mostly Syrians and Afghans fleeing conflict - have been trying to reach the European Union.

Record numbers crossing Med in 2015

Europe is on track to see a record number of migrants crossing the Mediterranean this year, according to the International Organization for Migration (IOG).

Italian officials say that as of Saturday, 103,000 migrants had been rescued at sea and brought to Italy in operations coordinated by the Italian coast guard.

Greece has reported 134,988 arrivals from Turkey this year through July, the IOG said. Along with refugees landing in Spain and Malta, 237,000 people have made the crossing so far this year, the agency says - compared to 219,000 for all of 2014.

More than 2,100 people have died at sea trying to reach Europe. The death toll is causing some soul-searching in Europe on how to manage the crisis.

Libyan chaos a factor

In Libya, smugglers take advantage of the chaos and fighting among tribes and militias in violence that's escalated following the 2011 ouster and killing of Libyan dictator Moammar Gadhafi.

So far diplomatic efforts have failed to form a unity government out of the rival factions ruling different sections of Libya.

"Either the international community is able to resolve the Libyan question, or today's (migrant tragedy) won't be the last," Alfano said.

jar/bk (AFP, Reuters, AP)