Chagos Islands: Mauritius’s latest challenge to UK shows row over sovereignty will not go away

The Conversation

A superyacht hired by Mauritius recently set out to conduct a scientific survey of the Blenheim reef, 230km off the coast of Diego Garcia in the Chagos archipelago. A group of Chagossians accompanied the scientists in what has been hailed as an “historic” event by Mauritian prime minister Pravind Jugnauth.

This trip was controversial not only among Chagossians but also because the international legal status of the islands has been in contention for the past 60 years. The visit took in the outer atolls of Peros Banhos and the Salomon, the last to be inhabited by Chagossians before the British government removed them in the 1960s to establish an American military base in the archipelago.

This was the first time Chagossians were visiting their homeland without UK support. The Mauritian flag was raised by Mauritian officials on both atolls and on Blenheim reef. At stake is the issue of Mauritian sovereignty.

British involvement

The Chagos archipelago is a collection of seven coral atolls made up of over 60 islands in the Indian Ocean, about 500km south of the Maldives, midway between Tanzania and Indonesia. In the late 18th century French planters established coconut plantations and brought in enslaved people, initially from Senegal, and later labourers from Madagascar, Mozambique and India to work on these plantations.

Today many of those identifying as Chagossians are the descendants of these enslaved and indentured labourers. Some research refers to them as the islands’ indigenous people.

These issues are significant because of the historical and contemporary relationship of the UK, US and Mauritius with the islands. The Chagos islands, which were dependencies of Mauritius, came under British sovereignty in 1814, having formerly been part of the French empire.

Internationally, the islands were largely neglected until the cold war. In the 1960s the US and the UK jointly identified Diego Garcia, the largest of the islands, as an ideal location for a military base in the Indian Ocean. Consequently, in 1965, the UK government detached the Chagos islands from Mauritius and from Seychelles.

While some islands were already uninhabited, between 1967 and 1973 the remaining population, around 1,500 inhabitants, was removed and relocated. Some were resettled in Mauritius, some in Seychelles and some in the UK. Laws were subsequently passed by the UK government to prevent people resettling to the islands.

Britain created a new colony from islands formerly part of Seychelles and Mauritius (the former were returned to Seychelles on its independence in 1976)- the British Indian Ocean Territory (BIOT). In 1966 the UK and US concluded the agreement to establish a joint military facility on the BIOT island of Diego Garcia. The agreement was to last for 50 years with an option of a 20-year rollover which was triggered in 2016. The agreement now lasts to 2036.

Contemporary litigation

Considerable litigation has been brought before the UK courts and the European Court of Human Rights by Chagossian Oliver Bancoult and as a group action by the Chagos Islanders regarding the right to return to the islands. In recent years there have been three important decisions.

In 2010, the UK established a no-fishing protected area around the Chagos archipelago. Mauritius claimed this infringed Mauritian fishing rights and instituted proceedings against the UK under international law.

In March 2015, the tribunal established under international law, to which the matter had been referred for arbitration, ruled in favour of Mauritius. It held that the UK had breached its obligations under international law and, in particular, the fishing rights of Mauritius.

Since Mauritian independence in 1968, consecutive governments have challenged the detachment of the Chagos islands, claiming they are part of Mauritius. In 2019, the International Court of Justice published an Advisory Opinion in response to a request from the United National General Assembly on behalf of Mauritius, stating that decolonisation had not been lawfully carried out.

In particular, it said that detaching the Chagos archipelago from Mauritius was not based on the free and genuine will of the people. Consequently, the UK’s continuing administration of the Chagos archipelago was unlawful.

The United Nations accepted this Advisory Opinion in a resolution that ordered the UK to withdraw from the archipelago within a period of six months. Almost four years on, the UK has still not done so. Instead the British government continues to hold that neither the International Court of Justice’s Advisory Opinion nor the UN resolution have any legally binding effect.

The UK has consistently indicated that it will cede the islands to Mauritius once they are no longer required for defence purposes. The UK has made a number of financial payments to Chagossians and is currently delivering about £40 million in support to improve the livelihoods of those in Seychelles, Mauritius and UK

Mauritius has said that the recent visit was not intended as a hostile act towards the UK. Nor was it an overture to resettlement. Nevertheless, it is a clear indication that Mauritius is not going to let the dispute of sovereignty disappear any time soon.


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Sue Farran does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.