Prime Minister Keir Starmer said he would not have appointed Peter Mandelson as UK ambassador to the United States had he known about email exchanges between Mandelson and convicted sex offender Jeffrey Epstein, and maintained he did not know the contents of those emails before defending Mandelson at Prime Minister's Questions.

Starmer told broadcasters it was "only on Wednesday, early evening, that I knew the contents of the Bloomberg emails" and that Mandelson replied to questions from government officials only very late on Wednesday, after the prime minister had taken part in PMQs. "What I knew before PMQs was that there had been media enquiries. I didn't know the content of the Bloomberg emails," he said.

Mandelson was removed from his post the following day after the publication of the email exchanges. The Foreign, Commonwealth & Development Office said the correspondence included a suggestion that Epstein's first conviction was wrongful and should be challenged, a development it described as "new information" that altered the understanding of Mandelson's relationship with Epstein and prompted his immediate withdrawal.

Downing Street has faced questions about when senior officials learned of the material. The Daily Mail reported that No 10 was told on Tuesday that the emails contained passages suggesting Epstein's first conviction was wrongful, citing a 2,000-word memo from Bloomberg seeking comment from Mandelson. Government sources have said that information was not shared with the prime minister before he answered at PMQs.

The timing of internal exchanges has drawn criticism in Parliament and from some within the governing party. Several MPs have called for action over what they say are gaps in the government's account of the timeline, and there has been public pressure on the prime minister's chief of staff, Morgan McSweeney, with some MPs saying he should be removed.

The fallout from the Mandelson episode compounded immediate political turbulence for Starmer, who was also dealing with the resignation on Monday of Paul Ovenden, his director of strategy, after historic WhatsApp messages of a sexual nature about senior Labour MP Diane Abbott were leaked. Downing Street said Ovenden had resigned following the publication of the messages.

The events add to a string of controversies since the prime minister outlined a "Phase Two" reset for his government at the start of September. On Sept. 1, Starmer carried out a reshuffle at No 10 and appointed Darren Jones as Chief Secretary to the Prime Minister as part of the reset. The process has been interrupted by a series of developments: on Sept. 3 deputy prime minister Angela Rayner admitted she had not paid enough stamp duty on a property purchase; she resigned from several cabinet positions on Sept. 5 after a probe found breaches of the ministerial code; on Sept. 9 US congressional releases of material connected to Jeffrey Epstein included a scrapbook that contained a handwritten note in which Mandelson described Epstein as "my best pal"; on Sept. 10 Mandelson told a newspaper that further "embarrassing" revelations about his relationship with Epstein could emerge; and on Sept. 11 Mandelson was removed after the publication of fresh emails.

Starmer said Mandelson had been through the standard due-diligence process for his appointment and reiterated that, "Had I known then what I know now, I'd have never appointed him." He defended his response at PMQs by saying he had confidence in the ambassador at the time because he had not seen the email content when questioned.

The prime minister is scheduled to make public appearances this week, including unveiling details of a proposed nuclear power deal with the United States, as the government prepares for a forthcoming state visit by former US President Donald Trump. Opposition parties and some MPs on the government benches have criticised the handling of the Mandelson matter and warned that the series of controversies is damaging the government's standing ahead of local and national votes.

No 10 and the Foreign Office have said senior officials were seeking answers from Mandelson as soon as the new material emerged and that the decision to withdraw him as ambassador followed the receipt of his responses. The prime minister's office said it would not comment further on personnel matters while internal inquiries and routine correspondence reviews continue.

The episode has intensified scrutiny of the recruitment and vetting processes for senior diplomatic appointments and of the flow of information within Downing Street. Parliamentary questions about the timeline of notifications to the prime minister, and calls for a fuller account of who was told when, are expected to continue in the days ahead.