Prime Minister Andy Burnham is facing a potentially difficult confrontation over the Chagos Islands at next month's United Nations General Assembly, with Mauritius reportedly preparing to press him to revive the stalled sovereignty agreement.
Two Mauritian government sources told The Telegraph that Mauritius intends to use meetings in New York to push Burnham to proceed with the deal transferring sovereignty over the Chagos Archipelago.
The reported plan has not been announced publicly by the Mauritian Government, meaning the claim about its intended approach at the UN remains attributed reporting rather than a formal diplomatic ultimatum.
Mauritius prepares to press Burnham
The Telegraph reports that Mauritian officials intend to raise the future of the Chagos agreement when Burnham attends the UN General Assembly in September.
The issue creates an immediate foreign-policy challenge for the new Prime Minister because the agreement signed by Britain and Mauritius in May 2025 remains in limbo.
Under that treaty, Mauritius would exercise sovereignty over the Chagos Archipelago while Britain would retain extensive rights over Diego Garcia to allow the strategically important joint UK-US military base to continue operating.
Trump opposition left agreement in limbo
The agreement was signed under the previous British government with US backing, but its implementation was subsequently thrown into doubt after President Donald Trump withdrew his support.
Trump criticised the proposed transfer of sovereignty and described it as an “act of great stupidity”.
The British Government subsequently acknowledged that legislation required to implement the treaty had run out of parliamentary time and would not proceed in that session.
At the time, the Government said it continued to believe the agreement was the best way to protect the long-term future of Diego Garcia but had always maintained that it would proceed only with US support.
Diego Garcia at heart of dispute
Diego Garcia hosts a strategically important joint British-American military facility used for operations across the Indian Ocean and beyond.
The 2025 treaty provides for Mauritius to become sovereign over the Chagos Archipelago while granting Britain rights over Diego Garcia for an initial 99-year period.
According to the House of Commons Library, the arrangement can be extended by a further 40 years if both countries agree, with scope for further extensions thereafter.
The agreement also provides for British financial payments to Mauritius and arrangements relating to environmental protection and potential Chagossian resettlement on islands other than Diego Garcia.
Burnham caught between Mauritius and Washington
The timing could prove particularly awkward for Burnham because his UN visit is also expected to form part of his first trip to the United States as Prime Minister.
British officials are preparing for possible talks with Trump during that visit, with Ukraine, defence, trade and the wider UK-US relationship expected to feature.
Burnham could therefore arrive in New York facing pressure from Mauritius to revive an agreement that the US President currently opposes.
No decision has yet been announced by Burnham either to restart the legislation, renegotiate the treaty or abandon the agreement.
Foreign Office stresses security of military base
The British Government has continued to emphasise the strategic importance of Diego Garcia.
Responding to the latest reporting, the Foreign Office said the base remains a key strategic military asset for both Britain and the United States and that ensuring its long-term operational security remains a priority.
The Government has previously said it will continue engaging with both Washington and Mauritius over a way forward.
That leaves the treaty signed but not brought into force, with its future dependent on political decisions in London as well as the positions taken by Mauritius and the United States.
Chagossian interests remain part of wider dispute
The future of the islands also remains deeply important to Chagossians, whose population was removed from the archipelago during the establishment of the military base.
The 2025 treaty includes provisions intended to support Chagossians and would allow Mauritius to pursue resettlement on islands other than Diego Garcia once the agreement enters into force.
Some Chagossians have opposed the sovereignty arrangements and criticised the process through which Britain and Mauritius negotiated the agreement.
Their position is therefore distinct from both the British and Mauritian governments' competing diplomatic priorities.
UN meeting could force decision back onto agenda
The reported Mauritian intervention threatens to return an issue that had effectively been placed on hold to the centre of British foreign policy.
Burnham inherited a signed treaty, stalled implementing legislation and a US administration that no longer supports the agreement in its existing form.
If Mauritius presses the Prime Minister directly in New York, he will face an early decision over whether to seek a route to revive the deal, attempt to renegotiate it or continue leaving it in limbo.
For now, however, Mauritius's intention to confront Burnham at the UN is based on reporting from Mauritian government sources, and no new agreement or British policy decision has been announced.