The ship sank about 100 miles off the coast of southern Italy, and was overloaded with African and Middle Eastern migrants, fleeing poverty and violence in typically unsafe and overcrowded boats, for European Union countries. Italy, and in particular the Italian island of Lampedusa in the Mediterranean Sea, are frequent destinations.
The incident came after a boat carrying migrants sank Sunday off the Libyan coast, killing at least 40 people.
The Italian Navy said 2,000 migrants were rescued in the past five days. The European Union border agency Frontex said tens of thousands are rescued in the Mediterranean annually.
The rescue operation initiated by the Italian government, called "Mare Nostrum," has saved the lives of over 20,000 migrants since October 2013, the United Nations' relief agency said. Nearly 43,000 migrants arrived by sea to Italy in 2013, it added.