A former police officer has lost his legal battle to overturn a conviction for assaulting a handcuffed man.

Ex-PC Darren Harris, 25, hit Emmanuel Frimpong in the stomach with a baton during an incident in Queen's Road, Brighton, last September.

He was fined £400 and ordered to pay £200 compensation and £400 costs after being convicted of common assault by Eastbourne magistrates earlier this year.

Yesterday Judge Guy Anthony up-held the decision and rejected an appeal against the conviction and sentence.

He also ordered Harris to pay an additional £500 costs.

Harris and fellow officers had been called to a convenience store in the early hours to investigate an allegation of shoplifting.

Mr Frimpong was arrested and as he was being led to the rear of a police van a struggle broke out.

Harris, who has since left the force, hit Mr Frimpong three times with his baton after the victim allegedly grabbed hold of a colleague's baton.

Mr Frimpong was later released without charge and the incident was reported by a CCTV operator.

The ex-officer, who now lives with his parents in Warwick where he works as an account manager with a sports equipment firm, claimed he had acted reasonably.

He told a hearing at Lewes Crown Court: "When I arrived there was no threat and I had no concern. It all appeared to be under control. Then I heard an officer shout 'Let go' and I became aware something was wrong.

"I moved myself round and could see Mr Frimpong had two hands firmly round the baton of the officer behind him. The officer said quite clearly, 'is there anything we can do to make you let go of the baton?'"

He told the court he used his baton to try to prise Mr Frimpong's fingers clear and then tried to jab his knuckles to make him release his grip.

He said: "The situation was clearly not in full control and I believed there was a real risk of serious injury.

"I delivered a low level strike which clearly failed. At that point another officer delivered a knee strike. I then struck the abdomen."

The court heard Harris failed to inform the custody sergeant at Brighton police station he had used his baton on the prisoner as required by police guidelines.

A second officer charged in connection with the assault, PC Anthony Spalding, 32 and formerly based in Brighton, was acquitted. His suspension has been lifted and he was said to be awaiting posting.

Last night Sussex Police said other officers are being investigated in connection with the case and they may face disciplinary proceedings.

A spokeswoman added: "A report on the incident is being considered by the Police Complaints Authority."