Senior figures in Prime Minister Sir Keir Starmer's government are preparing to hand over all private messages with Lord Mandelson, amid widespread anger over his appointment as the UK's ambassador to the US.

The prime minister has been under pressure to disclose the files after police launched a criminal investigation into claims Lord Mandelson passed sensitive government information to convicted sex offender Jeffrey Epstein.

On Thursday, Sir Keir apologised to the victims of Epstein for believing Lord Mandelson's "lies" and appointing him when the peer's friendship with the paedophile was already public knowledge.

But despite the prime minister's attempt to defuse the row, some of his own MPs are calling on him to stand down.

Migration Minister Mike Tapp said although this was a "difficult" time for the government, he had confidence in the prime minister.

"I'm pleased to see that the government will be completely transparent with this," Tapp said.

“We'll release the files, for example the vetting files, to show just how deceitful and weasley Peter Mandelson was and demonstrate the lies that he told.”The government has not indicated when it plans to publish any documents relating to Lord Mandelson's appointment publicly.

MPs have forced the government to give a cross-party parliamentary committee a role in deciding whether files considered damaging to national security or diplomatic affairs can be released.

The Intelligence and Security Committee of Parliament met on Thursday and in a letter to the prime minister, said it expected the documents to be put before MPs "very shortly".

But the Metropolitan Police, which is investigating Lord Mandelson, has told the government not to release "certain documents" that could undermine its criminal inquiry.

There is frustration in government over the Metropolitan Police's request.

The prime minister and other ministers have argued that Lord Mandelson lied during the vetting process about the extent of his relationship with Epstein, and they insist these documents will prove them right.

But the Mandelson files that the government must release go much wider than just that around his appointment.

They include all electronic communications - which could include WhatsApp messages and emails - between Lord Mandelson and government ministers, officials and special advisers during his time as ambassador.

That information has the potential to be embarrassing for people in government previously close to Mandelson, including Health Secretary Wes Streeting.

All of that information is likely to take several months to discover, and eventually publish.

No 10's former communications director warned the disclosure of private messages could drag more public figures into the scandal.