This report, long withheld and now published by the Guardian, highlights the only case of such extensive censorship by the NAO, with its findings initially made available to just two MPs.

The document's release concludes a decades-long effort by anti-corruption activists, who have repeatedly pushed for transparency over allegations of corruption in the £40bn deal.

The deal, concluded in 1985, involved supplying Saudi Arabia with 120 Tornado aircraft, Hawk jets, and more, with BAE Systems as the main contractor.

Documents indicate the MoD, led by then-permanent secretary Sir Michael Quinlan, misled Parliament and made secret payments to Saudi royals, including Prince Bandar bin Sultan.

Quinlan also claimed, falsely, that no public funds were used for commission payments to Saudis, a term often synonymous with bribes.

The NAO's buried report, uncovered in a public archive, hints at early evidence of financial misconduct, such as the MoD covering non-contractual expenses like cars and drivers for Saudi officials, totalling £88,000.

Despite these revelations, BAE has maintained that all payments were made with the UK government's approval, and the MoD contends the funds remained Saudi property, dismissing claims of corruption.

This revelation follows Guardian's probing into the MoD’s longstanding involvement in dubious payments to secure defence contracts, with recent transactions reported up to 2017.