A 50-metre sailboat with 22 people on board sank in the early hours of Monday off the coast of the Sicilian city of Palermo, and 7 people are missing, Italian media outlets reported.

Italy's Coast Guard and firefighters rescued 15 people, including a child, after the boat, flying a British flag, sank when a whirlwind and rough seas hit the area at sunrise.

The boat was carrying 2 Anglo-French citizens, an Irish national, a New Zealander and a Sri Lankan, news agency Adnkronos reported, while the rest were British.

The 15 people rescued are all in stable condition, Adnkronos said.

Divers from the fire department are continuing searches around the vessel, now at a depth of around 50 metres and half a mile off the coast.

The British foreign ministry had no immediate response to a request for comment.