Nigel Farage has claimed Sir Keir Starmer’s Chagos Islands deal will cost the British taxpayer £52bn over 99 years.

The Reform UK leader made the claim at a rally in Wiltshire today. He also took to Instagram to rubbish the PM’s deal, which will see the UK Government pay Mauritius for use of the Chagos Islands £90m a year for 99 years.

However, Mr Farage noted that the Mauritian Prime Minister, Navin Ramgoolam, claimed in the country’s Parliament that he had renegotiated Mr Starmer’s deal and that the annual payments were linked to inflation.

The Reform UK leader told his social media followers that if annual inflation was 3% then it would cost the taxpayer the same as “the entire [UK] Defence budget”.

“Starmer’s deal is going to cost you the taxpayer £50bn. They haven’t told us the truth”, Mr Farage claimed in an Instagram video.

“Is it because they’re incompetent? Is it because they’re simply liars? Or is it a bit of both?”, he asked.

He finished his impassioned speech: “£50bn. This deal must be stopped.”

In a separate speech, given at a Reform UK rally, the arch-Brexiteer said: “The total cost we will pay to the Mauritian government for this is £52bn.”

Discussing the need for the deal to be tied to inflation, Mr Ramgoolam said: “They had agreed to a package for 99 years, but not inflation-proof. The exchange rate — because it’s in dollars — would be fixed once and then last 99 years. How can that be?

“Any ordinary fifth-form, sixth-form student would agree that you know inflation exists. What is the point of having money and having half of it by the end? This is what would happen — we made the calculation.”

However, the UK Foreign Office denied that the taxpayer would be on the hook for tens of billions. “The UK will only sign a deal that is in our national interest,” a spokesperson said.