London’s High Court has refused permission for a legal challenge against the United Kingdom’s agreement with Mauritius over the future of the Chagos Islands, delivering a significant ruling in the long-running dispute surrounding the remote Indian Ocean archipelago.

The case was brought by claimants including Bertrice Pompe, a British national born on Diego Garcia, who argued that the government failed to properly consult members of the Chagossian community before negotiating the agreement with Mauritius.

The challenge sought judicial review of the government’s decision to proceed with the arrangement, which would transfer sovereignty over the islands to Mauritius while preserving Western military access to the strategically vital base on Diego Garcia.

In its decision, the High Court declined to grant permission for the case to move forward.

The judge concluded that the arguments presented had already been considered and rejected in previous rulings by English courts, leaving no sufficient basis for a new judicial review to proceed.

The ruling represents a legal setback for campaigners who oppose the agreement and who have argued that displaced islanders should have been more directly involved in the negotiations.

Lawyers representing the claimants indicated that they intend to pursue further action by seeking permission to appeal the decision.

The contested agreement forms part of a broader effort to resolve the long-standing sovereignty dispute over the Chagos Archipelago.

Under the arrangement, Britain has agreed in principle to transfer sovereignty of the islands to Mauritius while securing a long-term lease allowing continued operation of the joint United Kingdom–United States military base on Diego Garcia.

The base is considered one of the most strategically important military installations in the Indian Ocean, supporting surveillance operations and regional security missions.

The proposed arrangement would allow the base to remain under Western control through a lease lasting ninety-nine years.

The Chagos Islands have been the subject of legal and diplomatic debate for decades.

Residents of the islands were removed between the late nineteen sixties and early nineteen seventies to make way for the construction of the military facility, and their displacement has remained a central issue in subsequent legal disputes.

In recent years, international legal bodies and diplomatic negotiations have intensified pressure to resolve the sovereignty question.

The United Kingdom and Mauritius announced their agreement in principle to settle the dispute through a sovereignty transfer combined with a long-term defence arrangement.

With the High Court declining to permit the latest legal challenge, the government’s policy direction regarding the archipelago remains intact for now, although further appeals or political debate could continue to shape the future of the agreement and the rights of the Chagossian community.