Barrett said MOPAC’s decision not to approve the deal was “obviously within the range of options” open to it.

He added that the mayor’s policing office and the Met were “working together on a new, competitive procurement” for the contract, and that Palantir was “free, and indeed positively welcomed, to participate in this new, lawful and transparent competitive process”.

The Met had said it wanted to use Palantir’s technology to speed up tasks such as searching through reports and phone data. It is already used by the NHS and the Ministry of Defence, while some police organisations have also used the company’s tech.

But MOPAC said the force had failed to present its procurement strategy in a “clear and serious breach” of procedure, and Palantir was the only bidder seriously considered for the contract.

Shortly after the £50m contract was blocked, Palantir’s UK chief executive Louis Mosley accused London Mayor Sir Sadiq Khan of “putting politics over public safety“.

Critics of Palantir have pointed out the company’s funding links to the CIA, leading to allegations around surveillance, its contracts with the Israeli Defence Force, and its co-founder Peter Thiel being a major donor to Donald Trump’s presidential campaign.