The UK government said that it has reached an agreement with Mauritius to guarantee the continuation of a military facility in the Pacific Ocean that is shrouded in secret.

Under a new agreement, which was announced on Thursday, Britain claimed it would accept Mauritius' sovereignty over the Chagos Islands and guarantee its ability to run a military post at Diego Garcia for the next 99 years at the very least.

The Foreign Office stated that once the two nations reach a political deal, the base's status will remain uncontested and legally secure.

"Today's agreement secures this vital military base for the future," stated Foreign Secretary David Lammy.

Diego Garcia is a remote island in the Indian Ocean strictly out of bounds to most civilians. On a rare visit a BBC reporter described it as secretive UK-US military base shrouded for decades in rumour and mystery.

In a joint statement The Prime Minister of the Republic of Mauritius and the Prime Minister of the United Kingdom said they reached an historic political agreement on the exercise of sovereignty over the Chagos Archipelago.

It added: “Following two years of negotiation, this is a seminal moment in our relationship and a demonstration of our enduring commitment to the peaceful resolution of disputes and the rule of law. Negotiations have been conducted in a constructive and respectful manner, as equal sovereign States, on the basis of international law, and with the intention of resolving all outstanding issues between the United Kingdom and Mauritius concerning the Chagos Archipelago, including those relating to its former inhabitants.

“Today’s political agreement is subject to the finalisation of a treaty and supporting legal instruments, which both sides have committed to complete as quickly as possible. Under the terms of this treaty the United Kingdom will agree that Mauritius is sovereign over the Chagos Archipelago, including Diego Garcia. At the same time, both our countries are committed to the need, and will agree in the treaty, to ensure the long-term, secure and effective operation of the existing base on Diego Garcia which plays a vital role in regional and global security. For an initial period of 99 years, the United Kingdom will be authorised to exercise with respect to Diego Garcia the sovereign rights and authorities of Mauritius required to ensure the continued operation of the base well into the next century.

“The treaty will address wrongs of the past and demonstrate the commitment of both parties to support the welfare of Chagossians. Mauritius will now be free to implement a programme of resettlement on the islands of the Chagos Archipelago, other than Diego Garcia, and the UK will capitalise a new trust fund, as well as separately provide other support, for the benefit of Chagossians.

“It will also herald a new era of economic, security and environmental partnership between our two nations. To enable this partnership the UK will provide a package of financial support to Mauritius. This will include an indexed annual payment for the duration of the agreement and the establishment of a transformational infrastructure partnership, underpinned by UK grant funding, to deliver strategic projects generating meaningful change for ordinary Mauritians and boosting economic development across the country. More broadly, the UK and Mauritius will cooperate on environmental protection, maritime security, combating illegal fishing, irregular migration and drug and people trafficking within the Chagos Archipelago, with the shared objective of securing and protecting one of the world’s most important marine environments. This will include the establishment of a Mauritian Marine Protected Area.

"The treaty will open a new chapter in our shared history, one that will continue to be based on mutual respect and trust as close Commonwealth partners committed to the security and prosperity of the Indian Ocean Region by resolving all outstanding issues between the United Kingdom and Mauritius." We have had the complete backing and cooperation of our close allies, the Republic of India and the United States of America, in achieving the political agreement that we have today.