Story highlights Italian cost guard rescues more than 4,000 migrants off Libyan coast Thursday

Greek authorities clear overwhelmed Idomeni migrant camp on Macedonia border

(CNN) As many as 30 migrants may have drowned when their boat sank off the coast of Libya on Thursday, the European Union's anti-trafficking naval operation said, a day after another boat capsized in the region, costing five lives.

The European Union's anti-trafficking naval force in the Mediterranean, known as Operation Sophia, said there may be 20 to 30 fatalities from the latest sinking in the Mediterranean Sea, about 48 to 64 kilometers (30 to 40 miles) off Libya.

The Italian coast guard said it could not confirm the fatalities, but said it rescued 96 people from the vessel.

Those rescued were among more than 4,000 migrants rescued in the Mediterranean in 22 locations Thursday, it said.

The latest fatalities came a day after at least five migrants died off the Libyan coast when their ship rolled and then capsized. The incident occurred when hundreds of migrants rushed to the port side of the vessel as an Italian navy ship approached.