Mauritius prime minister says he has issued 'counterproposals' to UK on Chagos Islands deal.

A historic deal for the United Kingdom to hand over control of the Chagos Islands to Mauritius has been thrown into doubt after the African island nation's new prime minister issued "counterproposals".

The British government still plans to hand over control of the 60-island chain to Mauritius under the condition that a strategic joint UK-US military base on the largest of the islands, Diego Garcia, remains under British control for at least 99 . years.

Mauritius Prime Minister Navin Ramgoolam, who took office last month, said on Tuesday he was reopening negotiations because the current agreement "will not yield the benefits that the nation can expect from such an agreement".

Ramgoolam told lawmakers in Mauritius's parliament that his government was "still prepared to do a deal with the United Kingdom" and tabled counter-proposals.

Britain's Minister for British Overseas Territories, Stephen Doughty, said on Wednesday he was confident the deal would be finalized and that it was "completely understandable" for the new Mauritian government to seek time to review the details.

"I am confident that we have agreed a good and fair deal that is in the interests of both sides," he told lawmakers in the House of Commons. “It protects the base against proportional costs. It was supported by the national security architecture in the United States and by India."

The UK's opposition Conservatives accused the government of giving up sovereignty over a British territory.

US President Joe Biden hailed the agreement as "historic", stressing its importance for the future of the US naval base on Diego Garcia. However, supporters of US President-elect Donald Trump criticized the deal.

The base, which is home to some 2,500 US military personnel, has been described as an "all but indispensable platform" for security operations in the Middle East, South Asia and East Africa.

The Chagos Islands have been under British control since 1814. In the 1960s and 1970s, Britain forcibly evicted nearly 2,000 locals to make way for the US military base, which played a crucial role in US military operations in Vietnam, Iraq and Afghanistan. In 2008, the US also admitted that the base was used for secret flights of "terrorism" suspects.

The displaced Chagossians fought for years in British courts for the right to return to their homeland. Under the terms of the new agreement, they and their descendants would be allowed to return to the islands, although they would be excluded from Diego Garcia.

Mauritius, an African nation located about 2,100 kilometers (1,300 miles) southwest of the Chagos Islands, lies off the eastern coast of Madagascar in the Indian Ocean.