In a landmark ruling, the UK High Court has cleared the way for Britain to transfer sovereignty of the Chagos Islands to the African island nation of Mauritius. The decision ends a temporary block that had delayed the signing of the deal, which will allow the UK and US to retain their strategic military base on Diego Garcia for 99 years.

Prime Minister Sir Keir Starmer had planned to formalize the agreement on 22 May during a virtual ceremony with Mauritius, but a last-minute court injunction briefly halted proceedings. However, Judge Justice Chamberlain ruled to lift the injunction, enabling the handover to move forward.

A UK government spokesperson welcomed the decision, calling the agreement “vital to protect the British people and our national security.”

While the deal expands Mauritius’ territorial control in the Indian Ocean, it has sparked political backlash in the UK. Opposition figures, including Conservative leader Kemi Badenoch and Reform UK’s Richard Tice, have criticised the potential multi-billion-pound taxpayer cost and expressed concern over Mauritius’ ties with China.

Despite this, the Labour government maintains the move reduces legal risks and secures the future of the US-UK military base.

The UK’s Defence Secretary is expected to provide more details in Parliament on the military implications of the deal.