New files relating to Lord Peter Mandelson’s appointment as US ambassador are expected to be published by Christmas, can reveal.

The senior civil servant Cat Little has written to MPs, saying the Metropolitan Police has allowed the government to publish new files which were previously held back by the Metropolitan Police pending an ongoing investigation into Mandelson.

Little said the Met had previously asked the government not to publish a series of documents so that a criminal investigation on the former Labour grandee’s alleged leaks of sensitive information to the paedophile Jeffrey Epstein, who died in prison in 2019.

It is unclear what the new files will show or which part of his appointment they will relate to.

MPs on a security committee will now redact any information which may prejudice national security or international relations.

Documents in Epstein files at the beginning of the year appeared to show that Mandelson passed on confidential information about bailouts and Treasury assets to Epstein at around the time of the 2008 financial crisis. Mandelson was arrested on suspicion of misconduct in public office and released on bail. It was reported in the summer that an investigation was at risk of collapsing.

Mandelson files to return to Westminster

Sir Keir Starmer, who resigned as Prime Minister in the summer, came under considerable pressure over his handling of Mandelson’s appointment as US ambassador in 2024 and what security concerns were raised during a vetting process. Starmer’s former chief of staff Morgan McSweeney resigned over his involvement in Mandelson’s appointment.

Kemi Badenoch introduced a ‘humble address motion’, a mechanism which compels the government to release internal documents.

In the first batch of files released in March, exchanges showed security concerns over vetting were highlighted by Whitehall officials and national security adviser Jonathan Powell. The saga over vetting concerns led to the sacking of Sir Olly Robbins, who was then the Foreign Office’s top civil servant. A second release in June revealed discussions held between ministers and Mandelson at the time he was serving in Washington DC.

Documents featured some embarrassing remarks made by ministers, including the work and pensions secretary Pat McFadden. In one message, McFadden wrote about meetings with Labour MPs: “Every meeting I have is ‘who can we tax in order to pay benefits to others’. They’re asking the wrong questions.”

The Metropolitan Police and Cabinet Office have been approached for comment.