Three former Barclays bankers accused of funnelling secret fees to Qatar in exchange for emergency funding at the height of the 2008 financial crisis have been found not guilty of fraud, in a fresh blow to the credibility of the Serious Fraud Office.

Barclays’ ex-investment banking chief, Roger Jenkins; the former head of its wealth division, Thomas Kalaris; and the lender’s ex-European financial institutions head, Richard Boath, were accused of devising fraudulent advisory services agreements in order to disguise payments worth £322m to Qatar.

They were acquitted on Friday after the jury took less than six hours to clear the trio, all in their early 60s, following a five-month trial. It was the only criminal case brought against UK banking executives for their actions during the financial crisis. The case, which was brought by the publicly funded Serious Fraud Office, cost the taxpayer £9m-10m.

The SFO had alleged that the £322m paid to Qatar was actually a fee demanded by the Gulf state in exchange for investing £4bn in the bank as part of an £11bn emergency fundraising in 2008. That funding helped Barclays avoid a public bailout that would have placed it under government control.

According to the prosecution, the fees allowed Qatar to effectively purchase Barclays shares in the fundraising at a heavily discounted price that was not offered to other investors.

The acquittals are a major blow for the SFO, which also failed to win a separate trial against Barclays bank over the Qatar deal, which collapsed in 2018. The organisation later lost a high court appeal to reinstate the charges. Charges against former Tesco executives, accused of being masterminds behind a major accounting scandal, were also thrown out in December 2018 after a judge deemed the SFO’s case too weak to put to a jury.

An SFO spokesperson said: “Our prosecution decisions are always based on the evidence that is available, and we are determined to bring perpetrators of serious financial crime to justice. Wherever our evidential and public interests tests are met, we will always endeavour to bring this before a court.”

The SFO announced the charges in 2017 after a five-year investigation into the details of the rescue package. The fraud charges carried a maximum 10-year prison sentence.

A previous trial involving all three executives came to a close in April 2019, when the jury was discharged after four months of court proceedings. The former Barclays chief executive John Varley was a co-defendant in that trial but he was acquitted by an appeals court in June.

Barclays’ former finance director Christopher Lucas would have also faced charges in the latest case if he was fit to stand trial. He was not named as a defendant owing to an ongoing illness.

Commenting on his acquittal, Jenkins said: “I am very grateful that the jury, who sat through five months of evidence and speeches, concluded what I have known to be true all along, that I did nothing wrong twelve years ago in 2008. For the last eight years, since these investigations began, I have lived under a cloud over my private and business life.”

“I am conscious that the SFO plays an important role in the ethical functioning of our capital markets, however it is equally important that they are properly resourced to act fairly and expeditiously. I, and the others wrongfully accused, have been unable to work meaningfully for the years and years during these investigations and through this trial,” Jenkins added.

“This has taken an enormous toll on me both economically and personally, and I look forward now to rebuilding my life.

Boath said: “I’m delighted and relieved with this verdict, having been cleared by the FCA in July 2017. The SFO case was an invention and should never have been brought.”

Boath’s legal team at Peters & Peters is now calling on the attorney general to conduct a thorough review of the SFO. “After a series of high profile failures, the reputation of the SFO rested on this verdict. The government should now conduct an urgent independent review of the operations and decision-making at the SFO, with all options on the table,” senior partner Michael O’Kane said.

Barclays still faces a £1.6bn civil case over the Qatar funding later this year brought by businesswoman Amanda Staveley through her firm PCP Capital Partners. PCP, which represented Abu Dhabi investors during the 2008 fundraising, is alleging fraudulent misrepresentation and deceit over the terms given to potential investors. Barclays says it will defend itself against the claim and expects the trial to begin in June 2020.