The Italian navy says at least 40 migrants have died at sea and some 300 others have been rescued in the Mediterranean Sea north of Libya.

The navy said because the rescue was still ongoing Saturday it couldn't give exact numbers of dead and rescued. RaiNews24 TV, reporting from the Navy rescue coordination center in Rome, said the dead migrants were found in the hold of an overcrowded smugglers' boat.

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