Maltese and Italian vessels are searching for more than 20 migrants feared dead after a boat carrying them sunk 300 miles south east of Malta.

The operation started Friday after a merchant ship rescued two migrants who said a total of 30 had been on board.

The Italian Coast Guard rescued another seven migrants. The survivors, including two children, have been taken to Greece, the nearest landfall and within helicopter range.

Several corpses were spotted in the vicinity, and one has been recovered.

The numbers of migrants fleeing conflicts and risking the perilous sea voyages from Libya to Europe has swelled this year. Some 110,000 people have been rescued since January, and the U.N. refugee agency says at least 1,889 others have died.