A second former oil executive’s conviction for bribery has been overturned by the Court of Appeal, piling further pressure on the Serious Fraud Office’s beleaguered director Lisa Osofsky.

Paul Bond, 69, was jailed for three-and-a-half years last March for conspiracy to give corrupt payments following the SFO’s investigation into bribery involving the Unaoil energy consultancy. But his conviction was quashed today as a result of the SFO’s failure to disclose material about ‘wholly inappropriate’ contacts between a ‘fixer’ acting for the Ahsani family, which owned and controlled Unaoil, and senior officials at the SFO – including Osofsky.

David Tinsley, a former US Drug Enforcement Administration agent who was acting on behalf of the the Ahsanis, had regular contact with Osofsky and SFO investigators. He told the watchdog that he could persuade Bond’s co-defendant Basil Al Jarah to plead guilty, which he ultimately did.

Lord Justice Holroyde ruled that the SFO’s disclosure failures ‘prevented [Bond] from presenting his case in its best light’, rendering his conviction unsafe.

Mary Monson Solicitors, which represented Bond, said Osofsky’s position is now ‘wholly untenable’, and called on attorney general Suella Braverman to ‘consider the risk of even more innocent people being sent to prison at the hands of the SFO as long as Ms Osofsky remains in her job.

‘The conduct of the SFO, including those who made the crucial decisions regarding disclosure of this material, displayed an institutional arrogance which betrayed an air of untouchability,’ the firm said. ‘It seems other-worldly that the director of the SFO herself could have seen fit to meet with David Tinsley and correspond regularly with him during the case.’

They added: ‘Ms Osofsky behaved in a way well beneath the standards of any prosecutor in our legal system, and has damaged its reputation both domestically and abroad. She risked being a party to an unconscionable interference with a criminal trial and then the SFO sought to withhold from the court and lawyers the extent of what they had done. Answers are now required and judge-led inquiries, while welcome, do not deal with the immediate problem of Ms Osofsky’s continued presence as head of one of the most important prosecution offices in the world.’

Today’s decision follows the quashing of former Unaoil executive Ziad Akle’s conviction for bribery in December, which prompted Braverman to announce an independent review led by former High Court judge and former director of public prosecutions Sir David Calvert-Smith.

The Gazette understands that the SFO is disappointed with today’s ruling.

Helen Taylor, a legal researcher at anti-corruption charity Spotlight on Corruption, said: ‘The quashing of a second Unaoil conviction without the prospect of a retrial leaves the SFO very badly damaged. It raises serious questions about the SFO’s ability to bring home successful prosecutions in blockbuster bribery cases and comes hot on the heels of the botched disclosure which led to the costly collapse of the Serco trial.

‘In the wake of these disclosure disasters, it’s vital that the attorney general’s review is brought forward, that the findings are published in full and that lessons are learned quickly. As the UK’s key enforcer against corporate criminality, the SFO is too important to be limping rather than sprinting.’