Sir Keir Starmer rejected calls to resign after he axed the head of the Foreign Office in the Mandelson scandal which was threatening to end his premiership.
Sir Olly Robbins is leaving his post after it emerged the department overruled a security vetting process to clear Lord Peter Mandelson to become UK ambassador to the US despite his links to paedophile financier Jeffrey Epstein.
Speaking in Paris, where he was co-hosting a summit with French president Emmanuel Macron on the Iran war, he said it is "unforgivable" that he was not told Lord Mandelson had failed to pass security vetting for the role of ambassador to the US.
The Prime Minister said he was "absolutely furious" and it was "staggering" that he had not been informed the Foreign Office had overruled the recommendation from specialists in the UK Security Vetting team.
Sir Keir faced growing calls to quit over the scandal, with Labour leader in Scotland Anas Sarwar repeating his position that the PM should go, branding the Mandelson storm a “tipping point”.
Opposition parties accused the PM of misleading Parliament over the peer’s appointment to the top diplomatic post by saying full due process had been followed including over vetting.
But the Prime Minister stressed: "That I wasn't told that Peter Mandelson had failed security vetting when he was appointed is staggering.
"That I wasn't told that he had failed security vetting when I was telling Parliament that due process had been followed is unforgivable.
"Not only was I not told, no minister was told, and I'm absolutely furious about that."
But senior MPs questioned whether the Foreign Office’s top civil servant would have acted alone, and without political guidance on such a crucial issue.
Darren Jones, Chief Secretary to the Prime Minister, accepted that Lord Mandelson would have been able to see secret documents despite having initially failed security clearance.
He said he had ordered an urgent review after discovering that the Foreign Office and other Government departments had the right to ignore security advice when appointing people to sensitive roles.
Asked on BBC Breakfast whether the Prime Minister was going to resign, and whether he has either knowingly or unknowingly misled Parliament, Mr Jones responded "no".
But Dame Emily Thornberry, chair of the Commons foreign affairs committee, challenged the idea that Sir Olly acted alone.
She said: “The question is was it Olly Robbins who was a senior civil servant who had only been in the post a couple of weeks and who is going to say ‘this political appointment, they failed their security vetting, I’m going to decide all by myself that I’m going to override this and have him appointed anyway’.
“Or was he being pushed by someone else?”
Reform UK leader Nigel Farage said Sir Olly is the "sacrificial lamb in an attempt to try and save the Prime Minister".
He told LBC: "None of this adds up, the idea they weren't told about the vetting. Remember, in the House of Commons, Starmer actually said that the vetting had told him about the ongoing relationship with Jeffrey Epstein, then outside of the House, in Hastings, he gave a speech in which he said that Mandelson had cleared security vetting.
Security officials initially denied Lord Mandelson clearance, but Foreign Office officials took the rare step of overruling the recommendation.
The Government says Sir Keir was not aware that the former Labour grandee was granted developed vetting against the advice of UK Security Vetting until earlier this week.
He has instructed officials to establish the facts about why vetting was granted, and the Foreign Office earlier said it is “working urgently” to comply.
David Lammy, who was Foreign Secretary when Lord Mandelson was appointed, also did not know the Foreign Office had overruled the vetting until Thursday afternoon, it is understood.
A Government spokesperson confirmed that “officials in the FCDO” had taken the decision to grant developed vetting against the recommendation.
The Prime Minister has faced calls to stand down over the matter, with Conservative leader Kemi Badenoch calling it “preposterous” to claim he did not know Lord Mandelson failed security vetting.
She said: “If the Prime Minister doesn’t know what’s happening in his own office, he shouldn’t be in charge of our country. He should go.”
Liberal Democrat leader Sir Ed Davey said Sir Keir should have told Parliament “at the earliest opportunity” when he learned what had happened earlier this week, rather than having “waited for the media to force the truth out”.
The Green Party and Reform UK have also called for Sir Keir to resign.
Lord Mandelson, a political appointment rather than a career diplomat, was sacked from his Washington role last September when more details emerged about his relationship with Epstein, who died in 2019.
Sir Keir has been under fire over the decision to give Lord Mandelson the job despite it being known that his dealings with Epstein continued after the financier’s conviction for child sex offences.
Questions over his judgment intensified after the first batch of documents related to the decision published last month showed that he was warned before announcing Lord Mandelson’s ambassadorship of a “general reputational risk” over his association with Epstein.
That warning stemmed from the first part of the checks, carried out by the Cabinet Office, which was based on information in the public domain at the time.
The second was the highly confidential background vetting by security officials, which followed the announcement but came before Lord Mandelson took up his role in February 2025.
Information unearthed in this process – including any concerns – is never shared with ministers, and the result is binary, either clearing the candidate or barring them.
More documents relating to his appointment are yet to be released at the behest of MPs.
Sir Keir said in February that Lord Mandelson was cleared by security vetting, which he criticised for failing to disprove the former Labour grandee’s lies.
When Morgan McSweeney stepped down as Sir Keir’s chief of staff in February, he took “full responsibility” for giving his boss advice that resulted in the “wrong” appointment decision, while also calling for the vetting process to be “fundamentally overhauled”.
