The scandal around the vetting of Peter Mandelson when he was appointed as US ambassador deepened on Monday night.

It emerged in new documents that Mandelson was advised by Foreign Office officials to provide 'artificial' information about potentially compromising contacts in order to pass security checks.

The disgraced peer was asked repeatedly to provide 'sufficient' information about his personal and business connections. 

Emails released among numerous files on Monday show Mandelson, who was sacked as US ambassador last September over his friendship with paedophile Jeffrey Epstein, was asked to provide a list of 'overseas contacts' to identify 'potential security risks'.

Mandelson said he had a 'large number of personal acquaintances with foreign nationals' and asked officials: 'Do you mean literally every foreign national I have ever met?' 

He forwarded the exchange to the then-head of the US Global Issues Team at the Foreign Office, who suggested complying even if it was 'quite artificial'.

The official said: 'I suggest you send over the handful of names you mentioned, even though you don't consider them 'close contacts'. That will reassure the vetting team that you've been comprehensive, even if it's all quite artificial.'

This was despite concerns about Mandelson's well-documented associations with senior figures in China and Russia being raised during his vetting process.

Mandelson's links to a number of figures, including sanctioned Russian oligarch Oleg Deripaska, were flagged by United Kingdom Security Vetting, according to The Guardian, only to be dismissed by the Foreign Office.

Mandelson required Developed Vetting and 'Strap' Vetting – a codeword for an enhanced security clearance required for access to top-secret intelligence material.

The files show that officials were initially unsure what vetting he would require to head to Washington, as he was said to be considered a 'fit and proper person' as a member of the House of Lords.

Emails released on Monday show that civil servants reported that his vetting interview was conducted 'in good spirits' and that officials even asked Mandelson for 'feedback' because of high-level 'interest' in how it had gone.

The documents also suggest that, due to the pressure to get him in place before Donald Trump's 2025 inauguration, the Foreign Office gave Mandelson an exemption allowing him to view secret material before he had been cleared. 

During this period, emails show he was invited to a briefing with the then-Chief of MI6, Sir Richard Moore.

In response, a Foreign Office official warned Mandelson had not yet passed his vetting. 

The email read: 'Given the short time frame until his posting.. seniors here are giving him access to higher classification material on a case-by-case basis. I just wanted to ensure [Sir Richard] and your other seniors are aware, but it is of course for them to judge what is appropriate, given this rather unique case.'

It had been known at the time of his appointment that Mandelson had stayed at Epstein's home while the financier was in prison for child sex offences. But the true closeness between the pair was thrust into the spotlight by the release of the Epstein Files.

Ministers on Monday said that key questions put to Mandelson by Sir Keir Starmer's then-chief of staff Morgan McSweeney during the vetting process are being withheld on the request of the Metropolitan Police. 

They include questions about his relationship with Epstein. Mandelson is under investigation over allegations of misconduct in public office. 

He denies any wrongdoing.