The deal includes the tropical atoll of Diego Garcia, which is used by the United States as a military base.
The United Kingdom says it is giving up sovereignty of the Chagos Islands to Mauritius in a deal that would allow people displaced decades ago to return home while the UK retains use of the British-US military base on Diego Garcia.
The UK said on Thursday that the operation of Diego Garcia, a strategic military base jointly operated with the United States, was protected by the agreement, which also allows Mauritius to resettle the rest of the islands after its population was displaced.
“This government inherited a situation where the long-term, secure operation of the Diego Garcia military base was under threat, with contested sovereignty and ongoing legal challenges,” British Foreign Minister David Lammy said in a statement.
“Today’s agreement secures this vital military base for the future. It will strengthen our role in safeguarding global security, shut down any possibility of the Indian Ocean being used as a dangerous illegal migration route to the UK, as well as guaranteeing our long-term relationship with Mauritius.”
The UK, which has controlled the region since 1814, detached the Chagos Islands in 1965 from Mauritius – a former colony that became independent three years later – to create the British Indian Ocean Territory.
In the early 1970s, it evicted almost 2,000 residents to Mauritius and the Seychelles to make way for an airbase on the largest island, Diego Garcia, which it had leased to the US in 1966.
The International Court of Justice said in 2019 that Britain should give up control of the islands and said it had wrongfully forced the population to leave in the 1970s to make way for a US air base.
In a joint statement, Britain and Mauritius said that the political agreement had the support and assistance of the US and India.
“The treaty will open a new chapter in our shared history,” it said, as it “herald a new era of economic, security and environmental partnership between our two nations.”
The UK will provide a package of financial support to Mauritius, the statement added, to implement projects that boost the economic development of the country.
The two nations will also work together on issues including environmental protection, maritime security, drugs and people trafficking.