The UK’s claim to sovereignty over the remote Chagos Islands in the Indian Ocean has been ruled to be illegal by the United Nation’s highest court.
Although the majority decision by the international court of justice in The Hague is only advisory, the judges announcement is a further, severe blow to Britain’s prestige on the world stage.
The case was referred to the court, which hears rival legal submissions over international boundaries, after an overwhelming vote in 2017 in the United Nations assembly in the face of fierce opposition from a largely isolated UK.
In its submission to the ICJ last year, Mauritius argued it was coerced into giving up a large swath of its territory, the Chagos Islands.
That separation was in breach of UN resolution 1514, passed in 1960, which specifically banned the breakup of colonies before independence, lawyers for Mauritius said.
The UK government had told the court it did not have jurisdiction to hear the case. The ruling is expected to be referred back to the UN general assembly, where it will be debated.
The UK retained possession of the Chagos archipelago, which includes the strategic US airbase of Diego Garcia, after Mauritius gained its independence in 1968.
The UK government refers to it as British Indian Ocean Territory or BIOT. About 1,500 native islanders were deported so that the largest island could be leased to the US for the airbase in 1971. They have never been allowed to return home.