A Scotland Yard commander who was jailed yesterday for four years has become the most senior policeman to be convicted of corruption offences in more than 30 years.

Commander Ali Dizaei, a former president of the National Black Police Association (NBPA), abused his position to arrest and falsify a case against a web designer with whom he had a personal dispute.

A jury took just over two hours to find him guilty of misconduct in a public office and perverting the course of justice at the end of a four-week trial at Southwark Crown Court.

Mr Justice Simon told Dizaei, 47, who was acquitted of corruption charges in 2003, that he was guilty of “a grave abuse of public trust”. The judge said that he had to pass a deterrent sentence “to send a clear message that police officers of whatever rank are not above the law”.

Shy Dizaei, the officer’s third wife, sat behind the dock shaking her head as her husband was led away by a security guard to be taken to Wandsworth jail, southwest London.

Nick Hardwick, head of the Independent Police Complaints Commission (IPCC), which investigated the case, said that Dizaei was “a criminal in uniform” and “a bully”.

But the NBPA, for which Dizaei was a vocal spokesman, expressed surprise at his conviction. Charles Crichlow, the president, said that it was “clearly an extremely difficult and traumatic period for Dr Dizaei and his family”.

The officer was investigated after an incident in July 2008 when he arrested Waad al-Baghdadi, 23, who had built the website alidizaei.com to showcase Dizaei’s career and activism.

Mr al-Baghdadi believed that he was to receive £600 for his work but Dizaei repeatedly refused to pay him, and the two men confronted each other outside Yas, a Persian restaurant in Kensington, West London.

The designer said that Dizaei challenged him to a fight, then followed him into the restaurant and ordered him to leave. When he did so, Dizaei arrested and handcuffed him.

Much of the incident was recorded on CCTV and in a 999 call that Mr al-Baghdadi made to police. Dizaei also called 999 asking for “urgent assistance” and nine officers went to the scene. Witnesses were told by Dizaei to “back off”.

At Hammersmith police station, where Mr al-Baghdadi was detained overnight, Dizaei claimed that his wife had been threatened and he had been stabbed with a shisha pipe mouthpiece. However, a doctor concluded that his injuries were self-inflicted and the CCTV and 999 recordings supported Mr al-Baghdadi’s version of events.

Opening the case, Peter Wright, QC, for the prosecution, said that it involved “the wholesale abuse of power by a senior police officer for entirely personal and oblique motives”.

Dizaei became the most senior officer to be convicted since two Met commanders were jailed for corruption in 1977 because of their links with the Soho vice industry.

The IPCC will prepare a report for the Metropolitan Police Authority, which will then move to dismiss Dizaei for gross misconduct. He could also lose his pension. Dizaei has been suspended on full pay of £90,000 a year since September 2008.

Mr Hardwick said that the inquiry had uncovered a chain of events that could have led a corrupt policeman to send an innocent man to jail. “Dizaei behaved like a bully. Mr al-Baghdadi has shown tremendous strength of character throughout the case,” he added. “The greatest threat to the reputation of the police service is criminals in uniform like Dizaei.”

Sir Paul Stephenson, the Met Commissioner, said it was “extremely disappointing and concerning that this very senior officer has been found guilty of abusing his position and power”.

He added: “He has damaged not only his own reputation but that of the entire police service. Bearing in mind his rank, he should not be surprised at the severity of his sentence.”

Mr al-Baghdadi said: “I would like to thank all those who listened to me after I made my complaint, in particular the jury who have delivered justice and found Ali Dizaei guilty.”

Alfred John, of the MBPA, and a friend of Dizaei, said he was “very, very surprised” at the verdict. “When you look at how much was spent on this case and how much gets spent on the average murder case, you have to ask what was happening here.”

Members of the MPA can vote to order Dizaei to forfeit his pension. But first the Home Secretary must agree his crimes were “gravely injurious to the interests of the State” or liable to lead to loss of confidence in police.

With another six years’ service, Dizaei could have expected a pension of about £60,000 a year plus a six-figure lump-sum payout.

Times Recommends

• The battle for the Staffordshire Hoard
• Inside the crazy world of cage fighting
• Labour creates 4,300 new crimes since 1997