The Tory leader says Labour's negotiations could cost the UK billions; the prime minister questions whether Badenoch has been "properly briefed" on UK security.

A satellite communications system used by the US and UK to run military operations is central to efforts by Britain to resolve the sovereignty of the Chagos islands, UK security officials familiar with the matter said.

Britain and Mauritius denied on Wednesday media reports that London could end up paying double the amount in a renegotiated deal to retain a U.S.-British military base on Diego Garcia in the Indian Ocean.

Sir Keir Starmer has come under fire at PMQs over the cost of the government's deal to hand over the Chagos Islands to Mauritius. Earlier, the UK said newspaper reports that the effective price tag has jumped from £9bn to £18bn were "entirely inaccurate".

Britain's government insisted Thursday that it must hand back the Chagos Islands to Mauritius to secure continued access to satellite communications at a key US-UK military base.

If Britain wants to remain a reliable partner in our security alliance, it must be willing to defend its sovereignty. As much as President Trump uses unpredictability as a diplomatic tool, I can predict one thing for sure: there is no way he will allow Britain to give up its sovereignty over the Chagos Islands.