UK Parliament Debates Bill to Transfer BIOT Sovereignty to Mauritius

House of Lords Scrutinizes BIOT Sovereignty Bill

The UK Parliament's House of Lords has commenced the Committee Stage for the Diego Garcia Military Base and British Indian Ocean Territory Bill. This crucial legislative process follows a landmark treaty signed in May 2025 between the United Kingdom and Mauritius, which seeks to resolve the long-standing dispute over the sovereignty of the Chagos Archipelago, also known as the British Indian Ocean Territory (BIOT). The bill's passage through Parliament is a necessary step before the treaty can be ratified, giving domestic legal effect to its provisions.

The Committee Stage, a detailed line-by-line examination of the bill, began on Tuesday, November 18, with a second sitting scheduled for Tuesday, November 25. During this stage, members of the House of Lords are considering various amendments, including those related to the Secretary of State's duties concerning Diego Garcia and the financial payments to the government of Mauritius under the treaty.

Historic Agreement Redefines Chagos Archipelago's Status

The proposed legislation stems from a treaty signed on May 22, 2025, which represents a significant shift in the geopolitical landscape of the Indian Ocean. Under the terms of this agreement, the United Kingdom will formally recognize Mauritius' sovereignty over the entire Chagos Archipelago, including the strategically vital island of Diego Garcia.

Despite the transfer of sovereignty, the treaty ensures the continued operation of the joint UK-US military base on Diego Garcia. The UK will retain the right to exercise authority over the base for an initial period of 99 years, with provisions for potential extensions. In return for this arrangement and other cooperative measures, the UK has committed to paying Mauritius an annual average of £101 million over the 99-year period, amounting to approximately £3.4 billion in 2025/26 prices.

Addressing the Chagossian Community and Future Plans

A key aspect of the agreement addresses the historical injustices faced by the Chagossian people, the indigenous inhabitants who were forcibly displaced from the islands between 1968 and 1973 to facilitate the construction of the military base. The treaty allows Mauritius to implement a resettlement program on the outer islands of the archipelago, though not on Diego Garcia itself.

Furthermore, the UK will capitalize a new trust fund, to be established by Mauritius, specifically for the benefit of the Chagossians. This aims to support the community and address the long-standing issues surrounding their displacement and right of return. The agreement also outlines broader cooperation between the UK and Mauritius on environmental protection, maritime security, and combating illegal activities within the Chagos Archipelago.

A Resolution to a Decades-Old Dispute

The dispute over the Chagos Archipelago's sovereignty has spanned decades, with Mauritius consistently asserting its claim since the islands were detached from its territory by the UK in 1965. International bodies, including the International Court of Justice (ICJ) and the International Tribunal for the Law of the Sea, have issued advisory opinions supporting Mauritius' claim, adding international pressure on the UK.

The current bill and the underlying treaty aim to bring a formal resolution to this complex issue, marking a significant moment in the UK's decolonization efforts and its relationship with Mauritius. While the agreement has been largely welcomed as a step towards resolving historical grievances, some parliamentary debates and public discussions continue to focus on the specifics of the deal, particularly regarding the rights of the Chagossians and the long-term implications for the military base.