"The UN General Assembly has overwhelmingly voted for a resolution demanding Britain withdraw its administration of the Chagos Islands.
While the resolution is not legally-binding, it carries significant political weight.
The Indian Ocean archipelago is home to the Diego Garcia US military base.
In February, the International Court of Justice ruled the UK’s decolonisation of the Indian Ocean islands was unlawful.
The World Court said the UK acted illegally when it divided the territory from Mauritius in 1965 and later displaced thousands of islanders.
In a series of hearings in February, Mauritius told the court it was forced to give up the islands during the decolonisation process in order to gain independence.
Its representatives argued the archipelago had been part of its territory since at least the 18th century and was seized unlawfully by the UK.
The UK maintained Mauritius had given up the islands willingly, but the court found the agreement between the two countries at the time was not based on "the free and genuine expression of the will of the people concerned".
In response to the February ruling, Foreign Office minister Alan Duncan accused the UN General Assembly of a “misuse of powers” and of setting a “dangerous precedent”.