A British former executive at Monaco-based oil and gas consultancy Unaoil has been sentenced to three years and four months in jail for bribing Iraqi public officials to clinch $1.7bn worth of oil projects in post-occupation Iraq.

Iraqi-born Basil al-Jarah, Unaoil’s former Iraq country manager, admitted to paying $17m in bribes to secure contracts to construct oil pipelines, an oil platform and offshore mooring buoys in the Gulf, as the war-torn nation tried to shore up a battered economy after the fall of ex-president Saddam Hussein in 2003.

It is the third sentence handed down by a London judge after a five-year investigation by the Serious Fraud Office (SFO) and United States authorities into how the prominent Ahsani family, which ran Unaoil, secured energy contracts for Western blue-chip clients in the Middle East, Africa and Central Asia.

Former Unaoil managers Stephen Whiteley, 55, and 45-year-old Ziad Akle have already been sentenced to three and five years in jail respectively after a London trial.

“This was a classic case of corruption, where powerful men took advantage of the desperation and vulnerability of others to line their own pockets,” said SFO head Lisa Osofsky.

Al-Jarah’s lawyer did not immediately reply to requests for comment.

The SFO investigation originally centred on the Ahsanis, but failed extradition attempts culminating in a clash in Italy with US prosecutors over the extradition of Saman Ahsani in 2018 thwarted the agency’s attempts to prosecute them in the UK.

British prosecutors alleged 71-year-old al-Jarah, British-Lebanese Akle, and Whiteley, who is British, conspired with others to bribe public officials at Iraq’s South Oil Company and, in al-Jarah’s case, the Iraqi Ministry of Oil.

Akle and Whiteley denied wrongdoing. Al-Jarah pleaded guilty to five offences in 2019 and asked for further offences to be taken into consideration at his sentencing hearing on Thursday.

Whiteley and Akle, found guilty of conspiring to pay more than $500,000 in bribes to win a $55m oil contract, plan to appeal against their convictions, according to their lawyers.

Paul Bond, a 68-year-old former sales manager for former Unaoil client SBM Offshore, faces a retrial in January after the jury could not reach a verdict in his case.

Brothers Cyrus and Saman Ahsani, Unaoil’s British-Iranian former CEO and chief operating officer, await sentencing in the US after pleading guilty to bribery in 2019.