A potentially final dump of "Mandelson files" is expected next week, piling more pressure on Sir Keir Starmer as he battles to survive as prime minister.
Parliament's powerful Intelligence and Security Committee is meeting on Thursday and is expected to announce the release of the files after the meeting.
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But the committee is still locked in a last-minute battle with civil servants, diplomats and spooks over details they want kept secret from MPs and the public.
The committee was given the job of vetting the files after MPs voted to exclude only material prejudicial to the national interest or damaging to international relations.
Chaired by former Labour defence minister Lord Beamish, the committee also includes Tory attorney general Sir Jeremy Wright, Starmer ally Jessica Morden and a former First Sea Lord, Lord West.
Files released earlier this year revealed damning communications between former Washington ambassador Peter Mandelson and convicted paedophile Jeffrey Epstein.
Publication of the files is another potential nightmare for the prime minister because they could reveal more embarrassing details over Mandelson's appointment.
Files released previously provoked a furious political row as they revealed serious lapses in the vetting process, despite Sir Keir repeatedly telling MPs "due process" was followed.
Last month, the prime minister controversially and brutally sacked the top Foreign Office mandarin, Sir Olly Robbins, for failing to tell him about the lapses.
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Tory leader Kemi Badenoch accused the PM of a cover up and of misleading parliament, as she attempted to force an inquiry by the powerful privileges committee of MPs.
The release of the latest - and probably final - Mandelson files could not have come at a worse time for the beleaguered PM as he faces a likely leadership challenge from Wes Streeting.
(c) Sky News 2026: Final tranche of Mandelson files expected to be released next week
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