Mauritius has pledged to "spare no effort" to reclaim sovereignty over the Chagos Islands after a British plan to hand the remote Indian Ocean archipelago back to Port Louis was quietly shelved, following a withdrawal of American support under President Donald Trump.

Foreign Minister Dhananjay Ramful, speaking at a regional conference in Mauritius, said his government would pursue "every diplomatic and legal avenue" to complete what it describes as a long-overdue decolonisation process. "This is a matter of justice," he said. Mauritius's attorney general, Gavin Glover, struck a more measured tone, acknowledging that the outcome "does not come as a surprise" and blaming strained relations between Trump and UK Prime Minister Keir Starmer. Mauritius is expected to meet British officials on 22 April to discuss next steps.

The deal, originally agreed with the Biden administration, would have seen Britain formally cede sovereignty of the British Indian Ocean Territory — the official name for the Chagos Islands, which London has controlled since the 19th century — to Mauritius. In exchange, the UK and US would have leased back Diego Garcia, a critical joint military airbase on the islands, for 99 years at a cost of approximately £35 billion. However, UK government officials conceded they had run out of time to pass the necessary legislation within the current parliamentary session, after Washington declined to formally exchange letters amending the 1966 treaty that governs the islands. A new Chagos bill is not expected to feature in the King's Speech in May, when the government sets out its legislative agenda.

The collapse has drawn political fire in Britain. Conservative leader Kemi Badenoch welcomed the deal's failure, and other opposition figures have called for an inquiry into how negotiations were conducted. Health Secretary Wes Streeting pushed back on suggestions the deal was dead, insisting the UK remained committed to securing Diego Garcia's long-term future and that "lots of people in the US administration" still understood the strategic rationale. Former Foreign Office senior official Simon McDonald was blunter, telling BBC Radio 4 that with the US president "openly hostile," the agreement would go "into the deep freeze for the time being."

The stakes are significant. In 2019, the International Court of Justice ruled that Britain had unlawfully separated the Chagos Islands from Mauritius before granting Mauritius independence in 1968 — a process accompanied by the forced deportation of thousands of Chagossian islanders to make way for the military base. That ruling has kept sustained legal and diplomatic pressure on London. With Washington's position uncertain and the UK Parliament's session ending imminently, both the future of the base and the broader decolonisation question remain unresolved, leaving Mauritius determined but dependent on a thaw in Anglo-American relations to move forward.