Sir Keir Starmer is facing questions over what he knew about Peter Mandelson's friendship with paedophile Jeffrey Epstein before appointing him as the UK’s ambassador to the US .
The Prime Minister sacked Lord Mandelson from the role amid fresh revelations over his relationship with the disgraced late financier.
Sir Keir Starmer told the Labour grandee to “withdraw” from the role, a Foreign Office minister confirmed on Thursday morning.
It comes after emails, unearthed by the Sun and Bloomberg, show Lord Mandelson had supported Epstein when the banker was being investigated for sexual offences.
Stephen Doughty told the Commons that Britain’s most senior diplomat in Washington had been removed.
"In light of additional information in emails written by Peter Mandelson, the Prime Minister has asked the Foreign Secretary to withdraw him as ambassador to the United States,” the Foreign Office minister said.
"The emails show that the depth and extent of his relationship with Jeffrey Epstein is materially different from that known at the time of his appointment."
He added that Lord Mandelson's suggestion that Epstein's “first conviction was wrongful”, had been a major point in the Prime Minister’s decision to sack him.
Lord Mandelson is reported to have told Epstein to "fight for early release" shortly before he was sentenced to 18 months in prison.
He told him, "I think the world of you" the day before the disgraced late banker began his sentence for soliciting prostitution from a minor in June 2008.
Mr Doughty said: "In particular, Lord Mandelson's suggestion that Jeffrey Epstein's first conviction was wrongful and should be challenged is new information.
"And in light of that, and mindful, as we all are, of the victims of Epstein's appalling crimes, he has been withdrawn as ambassador with immediate effect."
In a further development on Thursday Sky News reported that it understood security services expressed concern about the appointment of Lord Mandelson but No 10 went ahead anyway.
The broadcaster said it had has been told by two sources that the security services flagged concerns as part of the vetting process for him being given the job.
No 10 did not judge these concerns as enough to stop the ambassadorial appointment, it claimed.
The prime minister's spokesman said vetting was handled by government departments and "any suggestion that No 10 was involved is untrue".
But it has has led to fresh questions over what the Prime Minister knew of Lord Mandelson's friendship with Epstein before appointing him and his judgement in doing so.
Conservative leader Kemi Badenoch said the latest revelations "point yet again to the terrible judgement of Keir Starmer".
She added that it is "imperative that all documents relating to Peter Mandelson's appointment are released immediately".
In a letter to staff at the embassy following his sacking Lord Mandelson said being ambassador had been "the privilege of my life".
He said he "deeply regrets" the circumstances around his departure and continues "to feel utterly awful about my association with Epstein 20 years ago and the plight of his victims".
Lord Mandelson this week spoke out about the scandal, admitting he feared more would come out and saying he had a “tremendous sense of regret” over his previous friendship.
It comes after the Prime Minister on Wednesday insisted he still had “confidence” in his ambassador when he faced questions in the Commons over a 2003 birthday note in which the peer described Epstein as his “best pal”.
The timing of his sacking causes a diplomatic headache ahead of Donald Trump's state visit next week, with the US president facing questions over his own ties with Epstein.
James Roscoe, the Deputy Head of Mission at the British Embassy Washington, has been appointed interim ambassador and will oversee MrTrump’s state visit, Downing Street has confirmed.
The Liberal Democrats have said the allegations surrounding Lord Mandelson "cast a damning shadow" and questions remain about what the Government knew.
Lib Dem leader Sir Ed Davey said the Prime Minister should come before Parliament to explain why he was appointed US ambassador in the first place when some details of his relationship with Epstein were already known.
"The Prime Minister now needs to appoint an ambassador who will stand up to Trump, not cosy up to him and his cronies,” Sir Ed said.
"He also needs to come before Parliament and explain why Lord Mandelson was appointed in the first place, given everything the Government knew then.
"This Government seems to be lurching from one crisis to another.”
Tory leader Kemi Badenoch said: “Peter Mandelson is now gone, but Keir Starmer failed yet another key test of leadership.
“I asked him about Peter Mandelson’s links to the notorious paedophile Jeffrey Epstein six times at Prime Minister’s Questions. And six times he could not provide any answers.
“He gave his full backing to a man unfit for office.”
Lord Mandelson's friendship with Epstein had been known about for many years, but emails appear to show that the relationship continued after the crimes committed by the financier had emerged.
The cache of documents obtained by Bloomberg showed that on the day before Epstein reported to jail in June 2008, Lord Mandelson told him "your friends stay with you and love you".
He said: "You have to be incredibly resilient, fight for early release and be philosophical about it as much as you can.
"The whole thing has been years of torture and now you have to show the world how big a person you are and how strong."
Lord Mandelson's position had appeared increasingly precarious in recent days after the release of the emails drew public criticism from members of the Government.
Health Secretary Wes Streeting said he was "completely disgusted" by the messages, while Home Office minister Mike Tapp said they were"really disturbing and sickening".
Sir Keir found the emails "reprehensible", Downing Street said.
Asked if the Prime Minister shared the view of his two ministers, Sir Keir's spokesman said: "I think it's self-evident that he found the content of these emails reprehensible.
Asked what aspect Sir Keir found reprehensible, he said the depth and extent of the relationship shown in the emails was "new information".
