To which country did the famous Robben Island prison belong to?

Robben Island is an island in Table Bay, 6.9 kilometres (4.3 mi) west of the coast of Bloubergstrand, Cape Town, South Africa. In 1961, the first black political prisoners were housed at Robben Island, and South Africa continued to use it as a prison until 1996. The most famous political prisoner held at Robben Island was Nelson Mandela.