UNITED NATIONS (Reuters) - The United Nations General Assembly asked the International Court of Justice on Thursday to give an advisory opinion on the legal consequences of Britain’s separation of the Chagos archipelago from Mauritius more than 50 years ago.

UNDATED FILE PHOTO- An undated file photo shows Diego Garcia, the largest island in the Chagos archipelago and site of a major United States military base in the middle of the Indian Ocean leased from Britain in 1966

The request came in a resolution adopted with 94 votes in favor, 15 against and 65 abstentions. The Hague-based court is the principal judicial organ of the United Nations.

Britain has overseen the region since 1814 and in 1965 detached the Chagos islands from Mauritius, a colony that gained independence three years later, to create the British Indian Ocean Territory.

It leased the archipelago’s biggest island, Diego Garcia, to the United States in 1966, paving the way for construction of an airbase that required the forced removal of some 2,000 people.

Diego Garcia became an important U.S. base during the Iraq and Afghanistan conflicts, acting as a launch pad for long-range bombers. The U.S. lease lasts until 2036. The United States joined Britain in voting against the resolution.

The General Assembly resolution requested the International Court of Justice to advise on whether the process of decolonizing Mauritius was lawfully completed, following the separation of the islands.

It also asked the court to advise on the “consequences under international law ... arising from the continued administration by (Britain) of the Chagos Archipelago, including with respect to the inability of Mauritius to implement a program for the resettlement on the Chagos Archipelago of its nationals, in particular those of Chagossian origin.”

Mauritius Minister Mentor Anerood Jugnauth told the General Assembly that “Mauritius, prior to its independence in 1968, had no legal competence, as a state, to give any consent to the detachment of the Chagos Archipelago from its territory.”

At the time of the separation, Britain paid Mauritius $3.8 million and pledged to cede the islands when they were no longer needed for defense purposes.

British U.N. Ambassador Matthew Rycroft said the issue should be discussed bilaterally and there was no need for an International Court of Justice opinion. He said Britain and Mauritius had held three rounds of talks since September.

“The Mauritian focus throughout the talks has not been the Chagossians, but Mauritius’ claim for sovereignty over the Chagos Archipelago,” he said.

The islanders who were moved were taken to Mauritius and the Seychelles and many eventually settled in southern England. The British Foreign Office said in November the government had decided against a resettlement in Chagos.