LONDON, Dec 10 (Reuters) - The conviction of Ziad Akle, a former Unaoil executive jailed last year for bribery, has been quashed and the UK Serious Fraud Office (SFO) accused of a "serious failure" in a damning judgment by London"s Court of Appeal. The Attorney General said it had commissioned an independent review after senior judges refused an SFO request for a retrial for the 46-year-old, who was jailed in 2020 for five years for conspiracy to bribe an Iraqi official to secure a $55 million oil deal after the fall of Saddam Hussein in 2003. Akle"s lawyer confirmed that he would be released on Friday. The ruling, made public on Friday, piles further pressure on SFO director Lisa Osofsky, raises questions about the convictions of Akle"s co-defendants and could rekindle a debate about the future of the SFO - a novel enforcement agency that combines investigatory and prosecutorial powers, lawyers said. The Court of Appeal said the SFO had failed in its disclosure duties, refusing to provide the defence with necessary documents to run their case and undermining Akle"s right to a fair trial. "That failure was particularly regrettable given that some of the documents had a clear potential to embarrass the SFO in their prosecution of this case," senior judges said. They did not suggest SFO officials had "deliberately sought to cover anything up". The SFO, which reports to the Attorney General"s Office, said it was assessing the judgment. But the Attorney General said it was "deeply concerned" about the findings and would be discussing the implications with Osofsky. Sarah Wallace, a partner for Constantine Law, said a failure to observe basic standards in high profile cases - even if not deliberate - risked diminishing the organisation"s credibility. Joseph Kotrie-Monson, director of Mary Monson Solicitors, which represents Akle"s co-defendant Paul Bond, said the decision opened the door to similar appeals for others. The SFO secured four convictions in its five-year investigation into Monaco-based energy consultancy Unaoil, founded and run by the prominent British-Iranian Ahsani family to help major Western companies secure energy projects in the Middle East, Central Asia and Africa over nearly two decades. Basil Al Jarah, Unaoil"s former Iraq partner, pleaded guilty in 2019. Akle, a one-time Iraq territory manager, former colleague Stephen Whiteley and Bond, a former sales manager for energy services company SBM Offshore (SBMO.AS), were subsequently convicted by jury in 2020 and 2021. Akle"s appeal against his conviction turned partly on the role of David Tinsley, who founded Miami-based investigative firm 5 Stones Intelligence and worked for the Ahsanis - the SFO"s one-time prime suspects, who have since pleaded guilty in the United States. The Court of Appeal said notes of a 2019 telephone conversation with Tinsley could support the case made by Akle"s lawyers - that senior SFO officers had engaged with Tinsley when he promised to try and secure guilty pleas from Akle and Al Jarah, although he did not represent them. read more "This judgment sends a clear message – the SFO can no longer engage in backroom deals," said Jo Dimmock, a Paul Hastings partner who represented Akle.