The government is facing legal action on two fronts after a court case that heard allegations that Britain facilitated the payment of bribes to high-ranking Saudis for decades.

Ian Foxley, a whistleblower who uncovered evidence of corruption in a long-running defence deal, is taking legal action against a government department, alleging that it blocked his attempts to uncover the truth. He said he had to flee from Saudi Arabia after being threatened with imprisonment.

A second government department is facing legal action from a businessman who was acquitted on Wednesday of paying bribes totalling nearly £10m to a Saudi prince and his associates. John Mason, 81, successfully argued that he had been unfairly prosecuted because the payments had been authorised by the British and Saudi governments.

The Serious Fraud Office, the anti-corruption agency, had initiated its prosecution after Foxley passed evidence to its investigators more than a decade ago.

Foxley, a senior financial executive, was working for a British firm, GPT Special Project Management Ltd, in 2010 when he discovered unexplained payments totalling millions of pounds that were being paid to offshore accounts.

The payments were part of a decades-long UK-Saudi defence contact in which GPT supplied military communications equipment to a Saudi unit.

Foxley, a former British Army officer, reported his concerns to senior MoD officials who then – without his knowledge – passed them to GPT and Saudi officials.

His boss and another executive, a Saudi princess, threatened to have him arrested. He believed that his life was in danger and, within 24 hours, flew back to Britain.

In his legal action, Foxley alleges that the MoD and GPT colluded in an unethical conspiracy that caused him to lose his job, forcing him to change career. He is alleging that he suffered mental stress.

Foxley said he wanted to hold the MoD and GPT to account for “the harm they’ve caused me, where they’ve consistently tried their hardest to conceal, obfuscate and block any access to the truth of what was really going on”.

In 2020, the SFO charged Mason and another businessman with paying bribes totalling £9.7m to Prince Miteb, the son of late King Abdullah, and other Saudi officials via offshore companies between 2007 and 2010 to ensure that GPT continued to be given large contracts.

Mason partly owned a firm that directed the payments to the Saudis via offshore bank accounts.

Mason and the second man were cleared of any wrongdoing in relation to the payments. They had argued that the British government had in effect authorised the exact type of payments that they were being prosecuted for.

Immediately after the verdict, Mason’s lawyer, Graham Brodie KC, told the judge that he would seek a legal order to force the MoD and the attorney general’s department to pay the cost of defending his client.

Brodie said the MoD had known about, and required, the payments for which his client was prosecuted. Had it not required those payments or, alternatively, had it admitted its involvement, he argued, it is likely the prosecution would never have been brought.

He said that had the attorney general not taken three years to approve the SFO’s prosecution, the case may never have proceeded. GPT, the MoD and the attorney general’s office declined to comment.

This article was amended on 11 March 2024 because an earlier version wrongly suggested that Graham Brodie KC would seek a legal order for the MoD and the attorney-general’s office to pay the cost of defending his client, on the basis that both departments were responsible for delays in the trial. Brodie would seek an order on the basis that it would have been likely that the prosecution may not have gone ahead, had the MoD not required the payments for which John Mason was prosecuted or had it admitted its involvement, and had the attorney general not taken three years to approve the SFO’s prosecution.