TUNIS—At least 17 African migrants drowned in a shipwreck off Tunis as they tried to cross the Mediterranean from Libya to Italy, the Tunisian Red Crescent said on Thursday. The Tunisian coastguard had rescued two Nigerian women in waters off the southern town of Zarzis, Red Crescent official Mongi Slim also told Reuters. The ship started on Sunday from Zawyia in Libya with 19 migrants on board. Last month, at least 40 migrants drowned off Tunisia’s port of Sfax south of Tunis. The United Nations said at least 300 people have perished in the central Mediterranean crossing this year while trying to get to Europe. The U.N. refugee agency UNHCR says fewer than 23,500 people have made its across the sea to Europe this year, with most new arrivals landing in Italy and Spain from Tunisia and Algeria. The agency estimates 633 people have died or gone missing on the …