Two people have drowned and some others were missing at sea after two merchant ships collided in rough seas off the Italian Adriatic coast, the Italian coastguard has said.

A Turkish ship sank after colliding with a vessel carrying a Belize flag in poor visibility about a mile from the Italian Adriatic port of Ravenna, a coastguard official said on Sunday.

Rescuers have saved four of the 11 crew members aboard the Turkish ship and have located and are trying to assist four others, the coastguard said.

He said the cause of the collision had not yet been determined, and that the Coast Guard was concentrating on rescue

Strong winds and choppy seas were complicating the search mission.