Tories to use ancient mechanism to force release of Mandelson vetting papers after criminal investigation launched

The Conservatives will today attempt to force the release of all information relating to Sir Keir Starmer's appointment of Peter Mandelson as ambassador to the United States after new revelations about his ties to Jeffrey Epstein.

Party leader Kemi Badenoch has demanded No 10 explain the vetting process after she claimed that concerns were "waived away" so the PM could make a "political appointment of a man who is a close friend of a convicted paedophile". It comes after the Metropolitan Police announced they had launched a criminal investigation into misconduct in public office offences after files released by US authorities appeared to show Mandelson had passed internal discussions from the heart of UK government to Epstein after the global financial crash.

Mandelson was business secretary in Gordon Brown's government at the time, was later made a life peer and last year was appointed the UK's ambassador to the US. He was sacked as ambassador in September, after new emails revealed he sent messages of support to Epstein even as the disgraced financier faced jail for sex offences in 2008.

His friendship with Epstein had already been known at the time of his appointment, but Number 10 argued it was not aware of its "depth and extent". The Conservatives will use their Opposition Day to table a humble address - an arcane mechanism that can compel the government of the day to produce certain documents.

The documents they will want to be published include due diligence work carried out by the Cabinet Office; emails between Mandelson and the PM's chief of staff Morgan McSweeney on his association with Epstein; minutes of meetings held about the appointment and details of payments made to Mandelson on his departure from the ambassador role. Humble addresses, if passed, are binding on ministers.

Several Labour MPs have told Sky News they were prepared to vote with the Opposition on the humble address. Left-wing MP Richard Burgon told Sky News' chief political correspondent Jon Craig that it would be "crazy" if the government opposed the motion, as "we can't have a situation where the government is dragged kicking and screaming to do the right thing".

Mrs Badenoch said Labour MPs "need to do what they know is right" and argued it "is about the reputation of our parliament and our country". She said: "I hope MPs of all parties, and especially those in Labour, will join us in fighting for the truth, for full justice for Epstein's victims and for openness and honesty with the British people.

"If the prime minister had a backbone, he'd allow his MPs to vote with their conscience and put their country before their party." No 10 added an amendment to the humble address calling for all documents to be published "except papers prejudicial to UK national security or international relations.