About 50 African would-be immigrants were Thursday feared to have drowned after their boat capsized off the Canary Island of Tenerife, DPA QUOTED Spanish officials as saying. Rescuers brought to safety 48 migrants, who said that between 100 and 105 people had travelled on the boat. A surveillance plane spotted the boat late Wednesday at a distance of 170 kilometres from Tenerife. As its passengers were being transferred onto rescue vessels amid four-metre-high waves, the boat capsized and many of the migrants fell into the Atlantic. Rescuers threw them life vests, but many were believed to have drowned. Rescue and commercial vessels, aircraft and helicopters were combing the area. Thousands of Africans are believed to have drowned while attempting to cross over to Spain.