British Indian Ocean Territory

General information

The British Indian Ocean Territory is close to the very centre of the Indian Ocean, mid-way between Tanzania and Indonesia.

Its nearest neighbours are the Maldives and Sri Lanka. The Territory covers 640,000 sq km of ocean (more than twice the size of the UK) but the land area is only 60 sq km.

The largest and most southerly of some 55 islands, Diego Garcia, accounts for more than half the land area. The other islands are very small, none larger than Hyde Park.

The islands were uninhabited until the late 18th century. The French established coconut plantations using slave labour in 1793.

After emancipation, many slaves became contract employees and remained on the islands. They were then referred to as Ilois but are now usually known as Chagossians.

The islands of the Chagos Archipelago have been British territory since 1814 when they were ceded to Britain with Mauritius (which then included the Seychelles).

For administrative convenience, and following the French practice, they were administered as a dependency of Mauritius until 1965 when, with the full agreement of the Mauritian Council of Ministers, they were detached to form part of the newly established colony of the British Indian Ocean Territory.

At the same time Britain paid £3 million to Mauritius in consideration of the detachment of the islands.

Three other island groups, formerly part of the Seychelles, made up the rest of the Territory, but these were returned to the Seychelles when it gained independence in 1976. The Government of Mauritius claims sovereignty of the Territory.

The UK does not recognise this claim but successive governments have given undertakings to the Government of Mauritius to cede the Territory to Mauritius when it is no longer required for defence purposes. In 1966 the UK agreed with the US to make the BIOT available for the defence purposes of the two countries.

The Crown purchased the freehold title to the land in the islands in 1967. The copra plantations were run down as their commercial future was already unviable, and the last of the contract workers and their children left the Territory in 1972/73. Successive British Governments have expressed regrets about the way resettlement was carried out.

Britain made £650,000 available to the Government of Mauritius in 1973 and a further ex-gratia sum of £4 million in 1982 to the Ilois Trust Fund in order to assist the resettlement of the contract workers in Mauritius.

The British Overseas Territories Act 2002 granted British citizenship to Overseas Territories citizens, including a large number of Chagossians.

This gave them a right of abode in the UK. Some Chagossians have brought a case against the UK at the European Court of Human Rights for the right to return to BIOT and for further compensation.

The BIOT has no permanent population, only UK and US military personnel and the civilian employees of contractors, who are mostly Filipino, reside within the territory.

The number of people on Diego Garcia varies significantly, depending on military needs. In early 2012 it was around 2,500.

There are no inhabitants on the other islands. Access to the BIOT is restricted and a permit is required. There are no commercial flights to the BIOT and permits are only issued to yachts in safe passage.

The British Indian Ocean Territory is not a tourist destination.


The BIOT is governed by a Commissioner, Deputy Commissioner and Administrator based in the FCO in London. The Commissioner’s representative in Diego Garcia is a Royal Navy commander who combines this role with his military duties as Commander British Forces.

The constitution of the BIOT is set out in the British Indian Ocean Territory Order 1976. The 1976 Order gives the Commissioner full power to make laws for the Territory.

Two Orders in Council in 2004 provided that there is no right of abode and imposed immigration controls. In the Territory, the Commissioner’s representative holds the office of Magistrate and is responsible for handling routine cases and also, through his subordinate oficers, for the enforcement of both the criminal law and laws regulating matters such as customs, immigration and conservation.

A series of exchanges of notes between the UK and the US regulates matters arising from the use of the Territory for defence purposes.

The current agreement runs until 2016 and allows for a roll-over for a further twenty years.



British Indian Ocean Territory

British Indian Ocean Territory – wildlife and heritage

British Indian Ocean Territory flag

British Indian Ocean Territory


British Indian Ocean Territory