Conservative leader Kemi Badenoch has accused the prime minister of misleading the House of Commons, after a report suggested Lord Mandelson failed his security vetting for the role of US ambassador.

The Guardian newspaper reported that the Foreign Office overruled the vetting decision to ensure the peer could take up the post.

Lord Mandelson was sacked as ambassador last year over his ties to the late convicted sex offender Jeffrey Epstein.

Reform UK and the Green Party called on Sir Keir Starmer to resign, while the Liberal Democrats said that if the PM had lied to the public "he must go". The government has been approached for comment.

During Prime Minister's Questions on 10 September 2025, Sir Keir Starmer said three times that "full due process" was followed for the appointment.

In response to the Guardian report, Badenoch pointed to his comments last September, adding: "We now know the prime minister misled the House.

"The prime minister must take responsibility."

The Ministerial Code states that ministers who knowingly mislead Parliament are expected to resign.

Taking questions from journalists following a press conference on 5 February in Hastings, Sir Keir said that "security vetting carried out independently by the security services, which is an intensive exercise that gave [Lord Mandelson] clearance for the role, and you have to go through that before you take up the post".

The Guardian said it was not known whether the PM was made aware Lord Mandelson had not been given security clearance by the vetting agency which carried out the checks, or who in the Foreign Office had made the decision to overrule this.

The BBC understands Lord Mandelson had no knowledge about the judgements reached during his vetting process until the Guardian article was published, and that no one at any level raised anything about it with him following his vetting interview process.

Reform UK leader Nigel Farage said: "Keir Starmer said in February that the security services had given Mandelson 'clearance for the role'.

"Now we discover that he has blatantly lied, the prime minister should resign."

Liberal Democrat leader Sir Ed Davey said: "Keir Starmer had already made a catastrophic error of judgement. Now it looks as though he has also misled Parliament and lied to the British public. If that is the case, he must go."

Green Party MP Sian Berry said: "Keir Starmer has lied and lied again over his decision to appoint Peter Mandelson and he must resign."

She added: "He has tried to blame the vetting process, when in fact it is reported that a decision was taken to ignore a failed vetting."

According to the Guardian, Lord Mandelson was initially denied clearance in late January 2025 after a developed vetting process.

The peer had already been announced as the UK's ambassador to the US in December 2024 and formally took up the role on 10 February 2025.

The developed vetting process is carried out by United Kingdom Security Vetting, a specialist agency within the Cabinet Office, and is designed to make sure individuals are unlikely to abuse their access to secret material, or be subject to blackmail or bribery.

It includes checks on a candidates' credit history and criminal record.

Those being vetted also have to undertake an interview with a specially trained vetting officer, which can cover areas including candidates' health, friendships, family and sexual history.

The government has already released documents related to an earlier due diligence check carried out by a team at the Cabinet Office, which was sent to the prime minister on 11 December 2024.

The advice - which is largely based on public information such as media reports - warned that Lord Mandelson's relationship with Epstein posed a "reputation risk".

Further documents are due to be released.

However, the Guardian reported that senior government officials have been considering whether to withhold documents from Parliament revealing Lord Mandelson was not given vetting approval from security officials.

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