At least 40 migrants died in the hold of an overcrowded boat while trying to cross the Mediterranean, Italy's navy said Saturday.
A rescue operation was underway to try and save hundreds of others on board the vessel, it said.
The victims are thought to have suffocated after inhaling fumes from fuel after the boat took on water in the hold, the captain of the navy ship leading the rescue said on Italian state television.
The Mediterranean has become the world's most deadly crossing point for migrants.
