The head of the European Union's border agency says its ships are working closer to conflict-torn Libya than ever but will enter those potentially dangerous territorial waters only to rescue migrants in trouble.

Frontex director, Fabrice Leggeri, said Thursday that the agency's patrol boats and aircraft "are approximately 80 nautical miles from the Libyan shore."

Around 75,000 migrants have been picked up trying to enter Italy and Greece from Libya so far this year. More than 1,800 are feared to have died. Most rescue emergencies happen some 40 nautical miles from Libya.

Frontex has been widely criticized for staying too close to Italy, but with new assets and a bigger budget, the agency has extended its work south to the edge of Malta's territorial waters.