Sadiq Khan may oppose Scotland Yard using Palantir’s AI systems to process criminal intelligence because of his “concerns about using public money to support firms who act contrary to London’s values”.

The mayor of London’s office made the statement after the Guardian revealed last week that Palantir, which works for Donald Trump’s ICE immigration crackdown and Israel’s military, has held talks with the Metropolitan police over a wide-ranging contract that could run into tens of millions of pounds.

The US tech firm, which was founded by the Trump-supporting billionaire Peter Thiel, demonstrated its systems to senior officers in the intelligence division at the UK’s largest police force last month. Intelligence staff have also been tasked with finding systems that AI could automate to increase productivity.

Khan has some power over any potential contract with the Met because any procurement above £500,000 must come to the Mayor’s Office for Policing and Crime for scrutiny and approval.

Khan’s public expression of concern comes after more than 330,000 people signed petitions in the UK calling for Palantir to be blocked or dropped from UK contracts. The government has a £330m deal for Palantir to process medical data in the NHS and a £240m deal with the Ministry of Defence. The former was signed by the Conservatives and the latter came after Keir Starmer, the prime minister, visited Palantir’s Washington showroom with Peter Mandelson, whose lobbying company, Global Counsel, worked for Palantir.

A spokesperson for the mayor said: “We can’t comment on live procurement processes. However, as a general point the mayor would have concerns about using public money to support firms who act contrary to London’s values.

“In considering any proposal, we review a variety of issues, including technical, financial, legal and data protection matters. In any such decision, our priority will always be the security of Londoners – including their personal data.”

Palantir recently released a 22-point manifesto which one MP described as the “ramblings of a supervillain”. It implied some cultures were inferior, called for an end to the “postwar neutering” of Germany and Japan and predicted a future dominated by autonomous weapons.

The Met is already using Palantir’s AI tools to try to detect rogue officers in its ranks, but that contract is understood to have fallen below the threshold for the mayor’s approval.

The increasing reach of Palantir is causing concern among politicians and campaigners. Thiel, who founded PayPal in the 1990s, has given lectures describing himself as a libertarian who is “worried about the antichrist” and wrote in 2009: “I no longer believe that freedom and democracy are compatible.”

It emerged last week that some Palantir staff have expressed internal dissent about the company’s work for ICE and the Israeli and US military. Some were aghast at the manifesto, which was published on X.com, with one saying: “It’s like we taped a ‘kick me’ sign on our own backs”, according to internal chat logs obtained by Wired magazine.

“Every time stuff like that gets posted it gets harder for us to sell the software outside of the US (for sure in the current political climate),” one staff member said in a message that was seconded over 50 times. Another wrote: “I’ve already had multiple friends reach out and ask what the hell did we post.”

Other significant internal concerns related to the company’s involvement in the US attacks on Iran, Wired reported. When a Tomahawk missile struck a girls’ school in Iran in February killing over 175 people, mostly children, one employee asked “Were we involved, and are [we] doing anything to stop a repeat if we were?”

Palantir has said AI technology more than doubled the pace of strikes in the first days of the war and it typically reduced collateral damage.

When Palantir’s chief executive, Alex Karp, said last month that AI would disrupt the power of female and Democrat voters and increase that of working-class males, one worker asked that if this was true “why are we cool with that?”

Khan’s intervention will feed into the global public relations battle facing Palantir. In Australia, there are calls for the country’s sovereign wealth fund to divest after making a $100m investment in Palantir.

Palantir has countered criticism by stressing that its software is highly effective. It says it has helped deliver 110,000 additional operations and reductions in discharge delays in the NHS, while police forces that have begun using it in the UK have praised it for speeding up investigations.

Palantir and the Met police have been approached for comment.

In a response to the Wired reporting, Palantir said: “We hire the best and brightest talent to help defend America and its allies and to build and deploy our software to help governments and businesses around the world.

“Palantir is no monolith of belief, nor should we be. We all pride ourselves on a culture of fierce internal dialogue and even disagreement over the complex areas we work on. That has been true from our founding and remains true today.”