An Italian coast guard said on Thursday, 17 migrants drowned after their boat capsized off the Libyan coast, as the victims were apparently asphyxiated by the engine, according to London media.

It said 20 people were saved, mostly from Nigeria and Ghana.

The guard said same day, 30 bodies were recovered from the hull of a boat carrying some 400 migrants, intercepted 50 kilometres north of Libya.

Meanwhile, the report said that two boats carrying migrants capsized off the same coast on Friday morning with hundreds feared dead.

It said information from local residents indicated that more than 100 bodies had been taken to hospital in the nearest town of Zuwara on the western Libyan coast, while hundreds more were missing.

It said through identifications, the bodies taken to hospital were of migrants from Syria, Bangladesh and southern African countries.

The report said coast guard managed to rescue 201 people, but many more were apparently trapped in the hold of the larger vessel.

It said the first boat, with 50 people, made signals for help when the second one carrying more than 400 passengers sank immediately.

A data from the UN indicated that in 2015, more than 2,000 migrants have died trying to cross the sea to Europe, with tens of thousands reaching Italy and Greece.

It said unprecedented numbers of refugees are braving the crossing as they flee war, persecution and poverty in the Middle East as well as Africa and Asia.