Keir Starmer's plans to hand the Chagos Islands to Mauritius received another damaging blow today, after an admiral who became a Labour security minister demanded he abandon the deal.

Admiral Lord West of Spithead, a former First Sea Lord who served as Labour's Security Minister under Gordon Brown, backed pa new paper accusing Sir Keir of making an 'unfathomable' mistake over the giveaway.

In the foreword to the report by the Policy Exchange think tank, Lord West argued that the planned surrender of the islands to China-ally Mauritius risked undermining the UK's relationship with the United States.

In the excoriating takedown of one of the Government's defining foreign policy decisions, Lord West argued: "For reasons that are difficult to fathom, the Government risks jeopardising both of these assets as it apparently remains determined to cede sovereignty of the Chagos Islands - the home of our vital Diego Garcia military base - to Mauritius.

"As I have argued elsewhere, surrendering sovereignty over the Chagos Islands would be an irresponsible act, which would put our strategic interests - and the interests of our closest allies - in danger.

Lord West dismissed Sir Keir's claims that the deal with Mauritius, which will cost Britain upwards of £9 billion over the next 99 years, makes the long-term future of the key military "more secure".

He wrote: "How can the base - which serves as an indispensable naval, air, and intelligence asset - be more secure under the sovereignty of another nation, rather than under our own?

"Developments since the proposed deal's announcement only several months ago demonstrate just how shaky its foundations are. American consent, which the UK Government has presented as so crucial to the negotiation, may well collapse with the arrival of the next Administration. The new Mauritian Government itself has in effect rejected the terms by re-opening negotiations to extract more cash.

"Meanwhile, the wide condemnation of the Chagossian diaspora, and neighbouring Maldives, punctures the argument that we have fostered goodwill with the 'Global South' by righting a past wrong."

This week it was revealed the Government is now offering to front-load some of the £9 billion pay deal to Mauritius in order to get the handover signed off before Donald Trump's inauguration on January 20.

The Labour grandee concludes that the agreement has been exposed as a "misbegotten act" after the newly-elected Mauritian government criticised the deal as something that "would not produce the benefits that the nation could expect".

Policy Exchange's security head Solarz Hendricks adds there is now "no good reason" to conclude the deal, and slams the Government for standing "on the brink of a senseless strategic unforced error".

While Foreign Secretary David Lammy has insisted that the US political establishment under Joe Biden has welcomed the deal, it's thought that China-sceptic Donald Trump will be much more opposed and could even veto it.

Mr Trump's pick for National Security Advisor, Mike Waltz, has been openly hostile to the deal, warning last year: "Should the UK cede control of the Chagos to Mauritius, I have no doubt that China will take advantage of the resulting vacuum."