Three children and one woman died and 21 people were rescued after their migrant ship sank off the Tunisian city of Sfax, Faouzi Masmoudi, a judge in Sfax, told Reuters on Wednesday.

He said all the migrants were Tunisians.

Tunisia has become a major departure point for migrant boats heading across the Mediterranean Sea towards Italy. (Reporting by Tarek Amara; Writing by Tala Ramadan; Editing by Kevin Liffey)