Sir Keir Starmer has come under fire at PMQs after Mauritius said the UK had agreed to change payment terms in its deal to hand it control of the Chagos Islands.
It comes after Mauritian PM Navin Ramgoolam claimed the UK had now agreed to front-load the payments and change how they are calculated.
The Conservative and Reform UK leaders both attacked Sir Keir over the cost of the deal, at a time when winter fuel payments to pensioners are being scaled back.
But Sir Keir insisting it was required to secure the future of a UK-US military airbase on the largest island, Diego Garcia, which the UK is due to keep on a 99-year lease.
Conservative leader Kemi Badenoch told MPs: “Yesterday, we heard the government offered £18bn for Mauritius to take our territory in the Chagos Islands.”
In response, the PM said: “This is a military base that is vital to our national security.”
He later continued: “A number of years ago, the legal certainty of that base was thrown into doubt. Let me be clear and I’ll pick my words carefully, without legal certainty, the base cannot operate in practical terms as it should.
“That is bad for our national security and it’s a gift to our adversaries.”
The deal to cede sovereignty of the archipelago, known officially as the British Indian Ocean Territory, was announced last October after a deal was reached with former Mauritian leader Pravind Jugnauth.
But he was swept from power in a general election a month later, and Ramgoolam, his replacement, has criticised the initial draft.
The agreement has also been mired in uncertainty after Donald Trump’s re-election as US president, given several US Republicans have argued it could deliver a potential security boost to China.
Mauritius says it was ready to sign a deal last month – but the UK asked to press the pause button to allow Trump to examine it first.
The UK government has never confirmed the estimated cost of payments under the deal, but press reports have put the figure at £9bn.
Speaking in the Mauritian Parliament on Tuesday, Ramgoolam said payments were due to be made in dollars and his predecessor had agreed the exchange rate would be fixed for the full 99 year-term of the lease.
But he added he didn’t agree with this, and the British side had now agreed on a different approach to the calculations, without offering detail.
