At least 80 migrants are feared dead after a boat capsized off the coast of Tunisia.  Four people were rescued from the inflatable vessel - which sank in waters near the town of Zarzis - but one died later in hospital, reports said. The three Malians who were rescued said that they had set out from Zuwara in Libya.  The country is a main departure point for migrants hoping to reach Europe. Libya has been torn by violence and division since long-time ruler Muammar Gaddafi was deposed and killed in 2011. Thousands of migrants, many from sub-Saharan Africa, are being held in detention camps in the country. On Wednesday at least 53 migrants were killed when a detention centre in Tripoli was hit by an air strike.  In May at least 65 people drowned when their boat set off from Libya and sunk off the Tunisian coast.