White House raises serious concerns over plans by Britain to hand over ... trends now

Diplomatic tensions with Washington were growing last night after Britain was poised to surrender a UK-owned territory to a close ally of China – even though the island hosts a highly sensitive Anglo-American military base.

Diego Garcia, which was first claimed by the UK in 1814, is likely to be handed to Mauritius as part of a transfer of sovereignty over the British Indian Ocean Territory, which comprises some 60 islands in the Chagos Archipelago.

The Mail on Sunday understands the White House has expressed 'serious concerns' about the plans due to the concentration of military hardware at the Naval Support Facility on the island, which has been called 'the unsinkable aircraft carrier in the Indian Ocean'.

The British base, which is leased to the US Navy, is home to some 1,700 military personnel and 1,500 civilian contractors, and includes port facilities, an airstrip capable of handling large aircraft, a support structure for submarine fleets, a sophisticated radar nerve centre and US Space Operations Command.

The Pentagon fears Beijing is looking for a similar military foothold in the region and even possibly on Diego Garcia.

Washington is increasingly concerned by the growing relationship between Mauritius and China. The two countries have already signed a free trade agreement as part of Beijing's 'Belt and Road Initiative' towards economic dominance.

News of the rising tensions came as world leaders yesterday warned China to halt its 'malign practices' and start 'playing by the rules'.

In a strongly worded statement, leaders of the G7, including Joe Biden, Rishi Sunak and Emmanuel Macron, told China that they are no longer prepared to tolerate its 'economic coercion' and military expansionism.

The leaders stated that while they are willing to build 'constructive and stable relations with China', that can only happen if the Communist superpower 'plays by international rules'.

Concern about Beijing's rise has been a key theme of the summit, as has its recent sabre-rattling towards Taiwan.

Last night, senior Tory MP Sir Iain Duncan Smith urged the Government to draw up a new agreement with Mauritius to resolve the 'strategic mess' over Diego Garcia.

He told The Mail on Sunday: 'The UK, with the USA, has to bring Mauritius on side with us, not with China. And that's got to happen now.

'The Government can't withdraw from there. They have got to come up with another agreement with Mauritius which will be more expensive but strategically critical.'