The UK has agreed to open negotiations with Mauritius over the future of the Chagos Islands, a British territory in the Indian Ocean since 1814.
Foreign Secretary James Cleverly said he wanted to “resolve all outstanding issues” over the archipelago.
The effective operation of the joint UK-US military base on Diego Garcia would be guaranteed, he added.
Chagossians have campaigned to return since more than 1,000 people were forced to leave in the 1960s and 1970s.
Diego Garcia is the largest of the 60 small islands of the Chagos archipelago. After the military base was established in 1966, the island’s inhabitants were expelled.
Mauritius, which won independence from the UK in 1968, maintains the islands are its own and Chagossians have fought for their return in the British courts.
The United Nations’ highest court, the International Court of Justice in The Hague, has ruled that the UK’s administration of the territory is “unlawful” and must end.
But until now the UK has resisted international pressure to begin talks about the islands.
In a written ministerial statement, Mr Cleverly announced: “The UK and Mauritius have agreed to engage in constructive negotiations, with a view to arriving at an agreement by early next year.
“Taking into account relevant legal proceedings, it is our intention to secure an agreement on the basis of international law to resolve all outstanding issues, including those relating to the former inhabitants of the Chagos Archipelago.”
The foreign secretary confirmed the negotiations would include “the exercise of sovereignty”.
The move follows talks between Liz Truss, during her short time as prime minister, and Mauritian leader Pravind Jugnauth at the United Nations General Assembly in New York in September.
