Ministers have been accused of hiding key information on Peter Mandelson as it emerged that a crucial file on his vetting will not be published.

The Cabinet Office will no longer release a summary document on the peer's security vetting ahead of his appointment as Britain's ambassador to the US after Scotland Yard advised that doing so could jeopardise any future prosecution.

The nine-page document compiled by the UK Security Vetting (UKSV) agency was set to be included in the second tranche of Mandelson files expected to be released as early as this week.

Last month it emerged that the vetting agency, part of the Cabinet Office, recommended Mandelson's vetting be denied. It is thought the UKSV was concerned about his associations, including in China.

Alex Burghart, Shadow Chancellor of the Duchy of Lancaster, said: 'The stench of scandal will continue to hang around Keir Starmer's Government until he is honest about who knew and when. The Cabinet Office briefed that the UKSV summary document would be published – it should honour that commitment.'

Last week senior ministers were accused of attempting to hide their messages with Mandelson. Officials reportedly had to ask for them multiple times before they were submitted by members of the Cabinet.

And the Intelligence and Security Committee, tasked with reviewing the Government's redactions on national security grounds ahead of the documents' release, said redactions on non-security grounds were 'being applied far too broadly'.

Any failures by Mandelson to declare a possible conflict of interest in the vetting process could constitute misconduct in public office.

A government spokesman said: 'We are committed to complying with the Humble Address [that forced the released of documents] in full. The second tranche of documents will be among the largest publications ever laid in Parliament.'