The UK's planned handover of the Chagos Islands to Mauritius should be considered by incoming US President Donald Trump before it goes ahead, Downing Street has said.

Efforts were made to get the treaty signed before President-elect Trump's inauguration on Monday, the BBC understands, and it had been expected the Mauritian cabinet would approve the proposal on Wednesday.

The UK plans to hand over sovereignty of the cluster of islands in the Indian Ocean, but to maintain a 99-year lease over the joint UK and US military airbase on the largest island, Diego Garcia.

A spokesman for Prime Minister Sir Keir Starmer said it was "perfectly reasonable for the US administration to consider the detail" of any agreement.

Shadow foreign secretary Priti Patel said the latest development was "complete humiliation" for the prime minister because Labour had been "desperate to sign off the surrender of the Chagos Islands before President Trump returns to office".

The deal has drawn criticism from other politicians in the UK as well as the incoming US Secretary of State Marco Rubio, who said it poses a "serious threat" to US security by giving the islands to a country allied with China.

Trump has not publicly commented on the deal. However Reform UK leader and Trump ally Nigel Farage told BBC Newsnight last year the agreement would damage Sir Keir's relations with the US president-elect.

At Prime Minister's Questions, Sir Keir defended the deal, saying the negotiations started under the last Tory government and insisting it was the best way to safeguard the military base.

Reports had suggested Mauritian Prime Minister Navin Ramgoolam would sign off an agreement on Wednesday as he attended a cabinet meeting, but it was later announced his attorney general was travelling to London to continue talks.

The UK took control of the Chagos Islands, or British Indian Ocean Territory, from its then colony, Mauritius, in 1965 and went on to evict its population of more than 1,000 people to make way for the Diego Garcia base.

Mauritius, which won independence from the UK in 1968, has maintained that the islands are its own, and the UN's highest court has ruled, in an advisory opinion, that the UK's administration of the territory is "unlawful".

Conservative leader Kemi Badenoch said the prime minister was "negotiating a secret deal to surrender British territory and taxpayers in this country will pay for the humiliation".

Badenoch said there was "no way we should be giving up British territory in Chagos", claiming Sir Keir was "rushing a deal which will be disastrous" and it would cost British taxpayers billions of pounds.

The cost of the proposed deal to the UK has not been officially announced.

In response to Badenoch, Sir Keir told PMQs the planned agreement would ensure the military base on Diego Garcia can continue operating effectively.

A deal over the Chagos Islands was first announced in October following years of negotiations.

But weeks later, after his election, Mr Ramgoolam said he had reservations about the draft treaty and asked for an independent review.

In a joint statement in October, Mauritius and the UK said the deal would "address wrongs of the past and demonstrate the commitment of both parties to support the welfare of Chagossians".

The Chagos islanders – some in Mauritius and the Seychelles, but others living in Crawley in Sussex – do not speak with one voice on the fate of their homeland.

Some have criticised the deal, saying they were not consulted in the negotiations.

Under the proposed deal, Mauritius will be able to begin a programme of resettlement on the Chagos Islands, but not on Diego Garcia.

UK Foreign Secretary David Lammy has previously played down the criticism, saying it is a "very good deal" for "our national security" because it secured the legal basis of the Diego Garcia military base.