What is the Chagos Island deal?

A UN panel has urged the UK to renegotiate a deal handing control of the Chagos Islands to Mauritius.

As part of the agreement formally signed by Keir Starmer last month, the UK will hand over sovereignty of the archipelago in the Indian Ocean while paying billions of pounds to continue using a joint US-UK military base on the largest island, Diego Garcia, under a 99-year lease.

A last-minute legal challenge from Chagossians living in Britain failed, but now a panel of four experts appointed by the UN Human Rights Council has called for the deal to be suspended because it "fails to guarantee" the rights of the Chagossian people, including the "right to return".

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The deal had overcome substantial hurdles and opposition from senior Republicans in the US, who feared it could end up benefiting China, as well as from "some inside the UK government who questioned why the UK was spending billions on it amid cost pressures", said The Guardian.

Why were the Chagos Islands British anyway?

The Chagos Islands, an archipelago of 58 islands in the Indian Ocean about halfway between Tanzania and Indonesia, were given to Britain by France in 1814 during the Napoleonic Wars. France ceded control of Mauritius and its dependencies, including the islands, which were valued for their coconut plantations and their position on trade routes between Africa and Asia.

In 1965, shortly before granting Mauritius independence, Britain separated the Chagos Islands, renaming them the British Indian Ocean Territory, and paying £3 million to Mauritius. The following year, Harold Wilson's government leased the largest island, Diego Garcia, to the US for use as a military base in exchange for a discount on Polaris nuclear missiles.

How did the agreement affect the Chagos islanders?

It required the expulsion of up to 2,000 or so Chagossians, French Creole speakers also known as the Illois – descendants of African slaves brought to work on the plantations. The British authorities, who described the islanders as "some few Tarzans or Man Fridays whose origins are obscure", drove them out by closing down the coconut plantations and, eventually, deporting the remaining residents to Mauritius and the Seychelles in the early 1970s. Many were left in the slums of the Mauritian capital of Port Louis, where suicides and addiction were common.

A long-running campaign by the Chagossians eventually led to the UK granting them £4 million in compensation in 1982, on condition that they renounced all rights to return home. Following further legal battles, in recognition of injustices they had faced, the islanders and their descendants were offered UK citizenship; many came from Mauritius to live in Crawley, near Gatwick, where they arrived.

How did Mauritius react to all this?

Mauritius has long claimed sovereignty over the Chagos Islands. It took the UK to the UN's International Court of Justice, which in 2019 found that the separation of islands from Mauritius was unlawful, and that the UK's continuing rule would be a "wrongful act".

This was only an "advisory" judgment, not a binding one, which the UK could have ignored, but it was politically damaging. In the same year, the UN General Assembly voted by 116 to six to condemn Britain's occupation of the islands, calling for it to end "as rapidly as possible". Only the US, Israel and a few others voted in support of the UK; even close Nato allies abstained. As a result, Britain entered into negotiations with Mauritius' government.

The deal to transfer the islands to Mauritius "has been praised for rectifying colonial wrongs done by Britain", said The Times, with the UN heralding the multibillion-pound deal as the liberation of "Africa's last colony".

The deal also underlines the "growing geopolitical importance" of Mauritius, said The Economist. Though small in land area, the island state claims a maritime zone spanning 2.3 million square km, roughly the same as the area of Africa's largest country, Algeria, and covering "important shipping lanes and potential mineral resources".

How might this affect the US?

The US had sought out the Chagos Islands as a military base during the Cold War. At the time, Diego Garcia was the only US base between the Mediterranean and the Philippines. Today, it is still regarded as vital strategically.

The prospect of Mauritian ownership is regarded with suspicion by many in the US, not least because Mauritius has close economic links to China. This posed a diplomatic conundrum for Britain.

How has Britain tried to solve this?

Under the treaty signed in May, Britain has ceded sovereignty of the islands to Mauritius but will also pay the Mauritian government to lease Diego Garcia, with an agreement that no other islands will be leased to rival powers.

The cost of the deal is £101 million per year for 99 years, amounting to around £10 billion over the course of a century.

This was thought, by the Labour government and UK officials, to be a satisfactory solution: righting historical wrongs and making sure that Britain complied with its legal obligations, but also safeguarding the military base for the foreseeable future.

However, "confusion remains over how much the deal will really cost" overall, said The Independent. "While the government has insisted the 'net value' of the deal will be £3.4 billion, because of the impact of inflation, in cash terms, some estimates have put it at as much as £30 billion over 99 years, assuming 2% inflation."

Why has it been criticised in Britain?

This has been seized upon by the likes of Reform UK's Nigel Farage, who asked how Starmer could justify the UK being "prepared to give away a military base and pay £18 billion for the privilege" (the government disputes that figure).

The Tories, who began negotiations when in power, have also come out strongly against it. The party has claimed that the deal will end up costing taxpayers "£5 billion more than previously feared" after ministers "admitted that the inflation figure they are using to calculate payments for future years is higher than previously thought", reported The Telegraph.

The PM has hit back at critics of the deal, claiming it is cheaper than the cost of running an aircraft carrier.

But the agreement has also faced opposition from the small community of Chagossians living in Britain, many of whom regard it as a betrayal.

How is it a betrayal?

The Chagossians who live in Britain, now numbering around 10,000, were given practically no voice in the negotiations. Some Mauritian Chagossians, such as the activist Olivier Bancoult, came out in favour of the deal. But the 3,500 in Crawley are, according to their MP Peter Lamb, near-universally opposed. They see Mauritius as a distant and hostile power, which treated exiles badly, withholding compensation paid by the UK for them.

Mauritius will face "very significant logistical challenges" to resettling the outer islands of the Chagos archipelago and it is "necessarily uncertain" that the Mauritian government will ever be able to do so, lawyers for the UK government have conceded.

The government admitted in April that Mauritius is unlikely to return any Chagossians to their homeland once the islands are ceded by Britain. There is similarly no guarantee that British Chagossians would be able to return to the islands, although Mauritians without roots there would, it seems, be able to.

A last-minute injunction brought by two British women born on the Chagos Islands was dismissed by the high court in May, finally giving the green light for the deal to be formally signed.

Diego Garcia: strategic asset

At the height of the Cold War, the US decided that it needed a strategic outpost in the Indian Ocean. Diego Garcia, a tropical atoll in the dead centre of the ocean and far from any threat, was ideal. Construction began in 1971. Today, Naval Support Facility Diego Garcia has an anchorage, an airstrip, and radar and communications facilities. It is home to about 2,400 people, mostly Department of Defence civilians. The roughly 400 US servicemen, and 40-odd members of the British Forces who live on the base see it as a plum posting, with its beaches and clear waters.

Diego Garcia's location allows for deployment of air and naval forces across the Middle East, East Africa and South Asia. It also provides a key refuelling and supply station. It is within striking distance of key maritime chokepoints, such as the Strait of Hormuz and the Strait of Malacca. US bombers from Diego Garcia played a major role in both Iraq wars and the war in Afghanistan in 2001; during the war on terror, it was a "black site" where al-Qaida suspects were interrogated. It has also served as a strategic deterrent to Iran and their Houthi proxies in Yemen.

The future of Diego Garcia under Mauritian sovereignty "carries significant implications for the US military posture in the Indo-Pacific and Middle East", said the Foreign Policy Research Institute.

Despite the PM's official spokesperson claiming the UK has "full control" over what happens on the base under the terms of the deal, there has been some "alarm" at a provision "which means the UK must inform Mauritius ahead of any armed attack on a third state directly emanating from Diego Garcia", said The Independent.

But while Mauritius' "growing economic dependence on China" brings up "concerns about potential strategic realignments under Beijing's influence", the FPRI concluded that Chagos deal guarantees the "continuity of US operations" and reaffirms Diego Garcia's "enduring role as a linchpin of American strategy in the Indian Ocean".