The UK will not finalise a deal to hand over sovereignty of the contested Chagos Islands to Mauritius until US President-elect Donald Trump’s administration is consulted.

The British government announced in October that it would cede sovereignty of the Indian Ocean archipelago but maintain control of a joint US-UK military base on the biggest island, Diego Garcia, under a 99-year lease.

However, some of Trump’s main allies opposed the agreement. Marco Rubio, Trump’s pick for secretary of state, warned last year that the deal posed “a serious threat” to US national security because Mauritius has a trade agreement with China.

A spokesman for UK Prime Minister Keir Starmer said on Wednesday it was “obviously now right” for Trump’s administration to consider any deal, which had already been approved by outgoing US President Joe Biden.

“It is perfectly reasonable for the new US administration to actually consider (it) and we will obviously have those discussions with them,” he said. “We will only agree to a deal that is in the UK’s best interests and protects our national security.”

Officials from the UK and Mauritius had been hurrying to complete the deal before Trump enters the White House on 20 January, according to British media reports. While the Mauritian cabinet had been expected to approve the deal on Wednesday, the British position “changed overnight,” a Mauritius source close to the negotiations told the BBC.

The UK took control of the Chagos Islands, which it called the British Indian Ocean Territory, from its then-colony Mauritius in 1965 — three years before the archipelago gained independence.

In the 1960s and 1970s, the UK evicted up to 2,000 people from the islands so that the US military could build the Diego Garcia base.

Mauritius has long contested the UK’s claim to the archipelago, and in recent years the United Nations and its top court have urged London to return the Chagos Islands to Mauritius.

The British government agreed to do so in the draft deal struck in October, but that has been delayed by a change of government in Mauritius and reported quarrels over how much the UK should pay for the lease of the Diego Garcia airbase.

A statement issued by the Mauritian government on Wednesday said that its cabinet had been “informed of developments” and that discussions in London would continue.

Additional sources • AP