Keir Starmer overruled officials who warned of a “reputational risk” in making Peter Mandelson US ambassador, despite being handed a dossier of evidence about the peer’s relationship with the sex offender Jeffrey Epstein, documents reveal.

The disclosure in newly released files will raise fresh questions about Starmer’s judgment – as well as about the vetting procedures at the highest levels of government.

The files show that Mandelson was offered a highly classified briefing from the Foreign Office even before he finished the formal vetting process.

They also show that two of the government’s most senior security and foreign policy officials – national security adviser Jonathan Powell and FCDO permanent secretary Philip Barton – raised concerns about Mandelson’s appointment due to his involvement in previous public scandals.

Despite the document prepared by the officials warning that Mandelson had continued his relationship with Epstein after his conviction, emails show close aides to the prime minister said they were “satisfied” with Mandelson’s explanations of their friendship.

The documents were released after the Conservatives forced the disclosures about the appointment of Mandelson, who was sacked in September last year because of new revelations about his close association with Epstein.

The documents show:

• Mandelson was offered a severance payment of £75,000 after initially asking the Foreign Office to pay him more than £500,000;

• Starmer was warned before appointing Mandelson that he remained in contact and stayed with Epstein after the financier was first convicted of procuring an underage girl in 2008;

• Powell told an investigation that he thought the appointment was “weirdly rushed”;

• Starmer was reassured about Mandelson’s friendship with Epstein by Matthew Doyle, his former communications chief and a friend of Mandelson. Doyle said he was “satisfied” with Mandelson’s explanation of the relationship.

Starmer has since said he believed Mandelson misled his team about the depth of his friendship with Epstein, including maintaining contact while he was in prison and urging him to fight for early release. Mandelson is understood to deny this.

In a note to the prime minister from December 2024, Starmer’s principal private secretary, Nin Pandit, said Mandelson’s relationship with Epstein had been discussed with Morgan McSweeney, Starmer’s then chief of staff, but that Doyle was “satisfied” with Mandelson’s answers.

The early documents from when Mandelson was first being considered as ambassador reveal that the prime minister was made aware his relationship with Epstein had continued beyond his conviction.

In the due diligence file, Starmer was warned there was “general reputational risk” around Mandelson’s links to Epstein. It enclosed information that was in the public domain – that Mandelson’s friendship continued “after Epstein was first convicted of procuring an underage girl in 2008, their relationship continued across 2009-2011 … Mandelson reportedly stayed in Epstein’s house while he [Epstein] was in jail in June 2009.”

The emails also suggest that official procedures were overridden to appoint Mandelson. One email shows that officials offered a high-level briefing to Mandelson shortly after his appointment had been announced.

An email dated 23 December from the head of the US & Canada department at the FCDO to Mandelson outlined his onboarding arrangements. In this email, the official states: “We’ll brief you further in person from 6 January onwards, including at higher tiers.”

An email does not formally confirm Mandelson’s developed vetting clearance until 30 January 2025, with his formal offer of employment.

Mandelson was asked then to apply for an even higher level of vetting – Strap clearance – which was not initiated until 4 February. The emails suggest he would have received higher tier briefings before either of these processes were complete.

The FCDO’s own security guidelines outlined in the formal appointment letter attached to that same email stated: “If Strap clearance is required … you should submit a new Strap application form for your new position at least three months before you are due to start at post.”

Speaking in the Commons after the release of the first tranche of documents, the chief secretary to the prime minister, Darren Jones, appeared to acknowledge the unorthodox timeline of Mandelson’s appointment and his subsequent vetting.

Jones said: “We are changing the process for direct ministerial employments, including politically appointed diplomatic roles, so that where the role requires access to highly classified material, the candidate must have passed national security vetting before such appointments are announced or confirmed.”

The cache of documents also reveals discussions about Mandelson’s dismissal as ambassador, which came after new documents were revealed in the US Department of Justice’s Epstein files, including emails where Mandelson urged Epstein to “fight for early release.”

Mandelson was offered a severance payment of £75,000 after initially asking the Foreign Office to pay him more than £500,000 for the balance of his contract, the newly released documents reveal.

Exchanges in the documents released by the Cabinet Office suggested officials did “well to get this settlement down this low with minimal fuss”, after Mandelson was sacked. Mandelson is understood to strongly dispute that he demanded the £574,000 mentioned in the documents, and that the sum was being used as a benchmark.

The documents suggest Mandelson raised the prospect of suing the Foreign Office for unfair dismissal until the settlement was reached. The department’s HR boss, Mark Power, said Mandelson had consulted an employment KC who said there were doubts about the “reasonableness of the PM’s decision” to sack him.

In an email, he wrote: “There is some carefully placed language around the public implications of not reaching a settlement, and the nature of an employment tribunal case … There is a potential, that absent a positive indication, Peter goes public on some of his claims so there is some urgency.”

Within the cache are also records of an internal investigation by Mike Ostheimer, the prime minister’s general counsel into Mandelson’s appointment after he was dismissed. They reveal that concern was raised about Mandelson’s appointment by two senior officials – Powell and Barton.

Powell told Ostheimer he had raised issues around Mandelson’s reputation directly with McSweeney, who said “the issues had been addressed”. Barton “also had reservations about the appointment”.

Opposition parties have called on Starmer to explain how Mandelson was potentially allowed access to classified briefings before the vetting process had concluded.

Alex Burghart, shadow chancellor of the duchy of Lancaster, said: “The lapse in the prime minister’s judgment knows no bounds. Allowing a scandal-ridden former minister access to highly sensitive information before proper clearance is completely careless. Even more troubling is that this happened while the government was aware of Mandelson’s longstanding, close connections to Epstein.

“Labour must come clean about what ministers knew, when they knew it, and why national security safeguards appear to have been treated so casually.”