Washington said the deal protected the long-term, secure and effective operation of the strategic military base.

Britain on Thursday said it would give up sovereignty of a remote Indian Ocean archipelago to Mauritius but will maintain there a strategic military base that it shares with the United States, in what US President Joe Biden described as a "historic agreement".

The UK government has announced that it will transfer sovereignty of a remote cluster of islands in the Indian Ocean to Mauritius. The final treaty outlining the transfer of the Chagos Islands, where there is a significant US military base, is expected to be announced in the coming months.