A boat crowded with migrants sank Monday in the Mediterranean just beyond Libya's territorial waters, leaving at least 14 dead, said the Italian Navy, which helped rescue more than 200 survivors.

The Navy said "at the moment 14 bodies have been recovered." There was no estimate of the number of possible missing because it wasn't immediately determined how many people had been aboard.

The sinking occurred some 160 kilometres south of the tiny Sicilian island of Lampedusa and about 65 kilometres north of the Libyan coast, Italian authorities said.

A Navy frigate and a patrol boat rushed to the scene along with two Italian Coast Guard boats and a boat from the Italian Border Police fleet. Medical personnel aboard the Navy boats gave assistance to the survivors.

Nationalities of the survivors and dead were not immediately reported.

In the past week alone, more than 4,000 migrants have reached Italy's shores, arriving in smugglers' boats. Many of the boats set out from Libya's loosely patrolled coast with migrants who are fleeing wars or hardship in Syria, Eritrea and elsewhere.