Chagos Agreement: A New Chapter for UK-Mauritius Relations
Uk-Mauritius Treaty
An overall settlement of the chagos saga is nearing completion
By David Snoxell
On 22 May 2025 a treaty was signed by the Prime Ministers of the UK and Mauritius bringing an end to nearly 60 years of tension in the bilateral relationship, the worst violation of human rights perpetrated by the UK in the 20th century, and the UK’s increasing international isolation over Chagos. Compliance with international law, UN General Assembly (UNGA) resolutions and the rulings of the International Court of Justice (ICJ) and other courts and tribunals will restore the UK’s reputation on the international stage as a law-abiding nation.
This treaty is the best outcome for Chagossians, UK, Mauritius, US, the UN and the rule of law. It has been achieved through diplomatic compromise. It opens the way to a new positive and productive bilateral UK/Mauritius relationship to the benefit of both countries which will be a key dimension to managing the complexity of the issues that are bound to arise in the early stages of treaty implementation.
Historical Background
It is nearly 60 years since the Chagos Archipelago was detached from Mauritius on 8 November 1965 and renamed the British Indian Ocean Territory to provide for a US baseon Diego Garcia. In the 1965 Lancaster House Agreement with pre-independence Mauritius, the UK gave a legally binding undertaking to ‘return’ the territory when no longer needed for defence purposes. The 55 Outer Islands were never needed. Although discussions about Chagos have taken place intermittently since 1982, the real negotiations only began in November 2022 under the previous British and Mauritian governments.
The UK’s gradual shift from resistance to negotiating an overall settlement took 25 years. It was brought about by international isolation, domestic and international litigation. The ICJ and the endorsement of its 2019 Advisory Opinion by the UN General Assembly, judgments by other international courts, UNGA resolutions going back to 1965, UN Human Rights bodies, the Commonwealth, African Union, SADC, EU, NGOs, academics, lawyers and diplomats have contributed to this outcome, not least the Chagos Islands (BIOT) All-Party Parliamentary Group (APPG) established in 2008 which held its 102nd meeting on 8 July.
Chagossians
The campaign for the return of the Chagossians began in the 1970s and involved nearly 20 years of litigation in the English Courts, known as the ’Bancoult litigation’. This major human rights issue attracted international support and helped focus world attention on Mauritius’ rightful claim to the territory.
The Chagossians were deported to Mauritius and Seychelles between 1968-73. The international community, Parliament and the public remained largely unaware of what had happened until details emerged in the late 1990s with the release of BIOT files. The litigation laid bare a tangled web of deception. It gave insight into the secretive nature of what had occurred and provided the foundation for international litigation. Officials, ministers, Parliament, the public and the UN were deceived into believing that the Chagossians were contract workers from Mauritius and Seychelles.
By far the largest Chagossian group, the Chagos Refugees Group (CRG) in Mauritius, led by Olivier Bancoult since 1983 supports the treaty. He told the APPG recently that most Chagossians support the treaty as the only way in which they will be able to return for visits and resettlement. Another Chagossian group that supports the treaty, and Mauritian sovereignty is the Chagos Islanders Movement. Others in the UK want BIOT to remain British.
The treaty provides for Mauritius to facilitate resettlement (though not on Diego Garcia) and a UK capitalised Trust Fund of £40million for the benefit of Chagossians. Organising what will probably be a trial resettlement is a huge undertaking and challenge for Mauritius, even if only a few Chagossians want to try it out.
Financial arrangements
The treaty contains detailed defence and security provisions to protect the base, its maritime zone, sea and airspace. While Mauritius regains sovereignty, Diego Garcia will remain under British control and administration. Mauritius will grant a 99-year lease with an option of a 40-year extension. The average annual cost to the UK at 2025/26 prices will be £101 million per year. Mauritius will be paid an annual sum varying between £165m (first 3 years) and £120m (next 10 years). Thereafter payments will be linked to inflation. There will also be an annual grant of £45m for 25 years to support economic and welfare projects in Mauritius. The total expected cost of the package is estimated at £3.4bn, not the £30bn often quoted. Financially Mauritius does well out of the deal.
Marine Protected Area
The treaty makes provision for the protection and conservation of the marine environment of the Chagos Archipelago and the creation of a Mauritian MPA for which the UK will provide scientific advice and support. This will be a considerable challenge though Mauritius has impressive experience with conservation and protection of the environment around its coastline and in the mountainous areas, including in Rodrigues,to draw on.
UK parliamentary involvement
The treaty along with 6 annexes, an Explanatory Memorandum and exchanges of letters were laid before Parliament on 22 May under the 2010 Constitutional Reform and Governance Act which requires 21 working days for consideration of a treaty by Parliament. This period expired on 3 July. Two House of Lords Committees (International Agreements; International Relations and Defence) heard evidence for and against the treaty including Foreign Office Minister Stephen Doughty, former ICJ judge Christopher Greenwood and Philippe Sandswho advised Mauritius on international litigation. The Committeereports supported ratification.
At the end of a 4.5 hours debate in the Lords on 30 June, an Opposition motion requesting the government not to ratify was defeated by 205 to 185 votes. This clears the way for ratification following a short bill to implement the treatyfor legal and administrative purposeswhich will wind up BIOT. The Diego Garcia Military Base and British Indian Ocean Territory Bill was introduced in Parliament on 15 July. Secondary legislation willfollow after the summer recess.
An Opposition Bill to keep BIOT British has been postponed until September but is unlikely to succeed. Ratification may be achieved within 6 months. The Minister undertook to address concerns expressed in the debate, especially resettlement, accountability of the Trust Fund and enhanced engagement with Chagossians.
A new chapter in Anglo-Mauritian relations
Chagos must hold the record in parliamentary history for the time it has taken to conclude and debate a treaty. The APPG considered it was a crucial landmark in the Chagos narrative and UK’s relationship with Mauritius. There has rarely been such a prolonged international, national, parliamentary and media debate on a foreign policy issue. Some 300 PQs have been answered since October along with numerous Urgent Questions, debates and government statements.
The APPG discussed its role now that its objectives for resettlement and an overall settlement of the issues (adopted in January 2009) have been largely met by the treaty. They agreedthat the APPG still had an important role to play in monitoring legislation to be passed by Parliament and then the implementation of the treaty. Members felt they had an important task in supporting the interests of Chagossians, such as resettlement, visits and the operation of the Chagossian Trust Fund. They also emphasised the need for the UK and Mauritius to continue to work closely together on all aspects of implementation or disputes that could arise. They felt that a new and positive chapter in Anglo-Mauritian relations was beginning.
David Snoxell has been Coordinator of the Chagos Islands (BIOT) APPG since 2008. He was British High Commissioner to Mauritius, 2000-04, and Deputy Commissioner of the BIOT, 1995-7
Mauritius Times ePaper Friday 18 July 2025
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