A knife-wielding criminal who was jailed after trying to rescue a suspected thief from a supermarket security room today lost an appeal against his sentence.

Sarfraz Anjum Shaheen, 39, answered the call for help from the other man after he was accused of shoplifting at Tesco in the Eden Centre, High Wycombe.

A battle ensued as security guards tried to detain Shaheen, during which one of them - Ben Ali - suffered a knife injury to his forehead.

Shaheen, of Green Street, High Wycombe, was jailed for four-and-a-half years at Aylesbury Crown Court in July.

He had admitted wounding Mr Ali, assaulting another guard and threatening a third with a knife during the incident in August last year.

The sentence also included punishment for theft and threatening a person with a knife, after an incident at Asda days earlier.

Shaheen and another man had been seen putting bottles of alcohol into a bag in a trolley, but when they got to the checkout, they only paid £30, leaving more than £500 worth of drinks in their bag.

When they were stopped, Shaheen pulled out a kitchen knife, which he used to make space to escape the store with his accomplice.

His lawyers today argued at the Court of Appeal that his total sentence was too long because he had been too harshly punished for wounding Mr Ali.

But rejecting his appeal, Mr Justice Foskett, sitting with Lord Justice Hamblen and Judge Mark Lucraft QC, pointed to his previous convictions.

He had eight offences on his record and had previously served a four-and-a-half year term for biting someone's ear.

Mr Justice Foskett said: "He had a history of the use of serious violence. In the present case, he deliberately armed himself with a knife on two separate occasions."