evidence: UK gives sovereignty of the Chagos Islands to Mauritius. The US base on Diego Garcia stays LONDON (AP) — The British government agreed Thursday to hand sovereignty of the long-contested Chagos Islands, an archipelago of more than 60 islands in the Indian Ocean, to Mauritius, in a deal to secure the future of a strategically important U.K.-U.S. military base. [...] The Chagos Islands, which conjure up images of paradise with their lush vegetation and long stretches of white sandy beaches, have been at the heart of what Britain has called the British Indian Ocean Territory since 1965 when they were siphoned away from Mauritius, a former U.K. colony that gained independence three years later. Mauritius, which lies east of Madagascar in southern Africa, is around 2,100 kilometers (1,250 miles) southwest of the Chagos Islands.