Around 30 migrants are feared dead after a boat they were travelling in capsized in the Mediterranean, off the Libyan coast, while more than 50 were rescued by EU vessels from the sea.

The alarm was raised by a Luxembourg reconnaissance plane which saw the capsized boat.

Ships from a European Union task force and Italy’s coast guard raced to the scene, around 65 kilometers off the coast as survivors clung to the hull or swam.

In another incident, the Italian Navy rescued 562 migrants from a boat that capsized on Wednesday.

This week alone, around 6,000 migrants trying to reach Europe have been rescued from flimsy craft in the Mediterranean.

Aid agencies say the crossing between Libya and Italy is the main route for migrants since an EU deal with Turkey curbed the number sailing across the Aegean to Greece.

“We estimate the dead to be between 20 and 30 people,” AFP reports Captain Antonello de Renzis Sonnino, spokesman for the EU’s Sophia military operation to combat people smugglers in the region, told AFP news agency to say.