Italy's coast guard says some 50 bodies have been found in the hull of a migrant boat that was rescued off Libya's northern coast.

Coast guard Lt. Claudio Bernetti said the Swedish ship Poseiden, which is taking part in the EU's Triton Mediterranean operation, rescued 439 surviving migrants from the ship Wednesday.

The rescue was one of 10 requests for assistance that arrived at the coast guard's operations center as Libya-based smugglers take advantage of calm seas to send boats overloaded with migrants to Europe.