The Co-op is banning evening sales of alcohol in Brighton and Hove after being caught selling to under-age drinkers.

Trading standards sent teenagers in under cover to buy drink and found many city Co-op branches willing to sell it to them.

Under-age drinking is seen as a major cause of antisocial behaviour on city estates.

The Co-op today said the "errors of judgement" by some members of staff were regrettable.

Branches in High Street, Rottingdean, and Warren Way, Woodingdean, were singled out and the Co-op has stopped the sale of alcohol in both stores from 4pm every Thursday, Friday and Saturday for the next six weeks.

A spokeswoman said: "We hope our customers will appreciate the reasons we are doing this. We are working with Brighton and Hove City Council and Sussex Police to combat antisocial behaviour."

She said Co-op staff were trained to challenge anyone looking under 21 to provide proof of age and young store attendants had to call a colleague over 18 when they sold drink. Records showed a large number of young people were being refused purchases.

The spokeswoman said: "It is regrettable there can be errors of judgement on the part of staff but it is difficult when some young people look older than their years.

"Antisocial behaviour is a growing problem across the United Kingdom and the Co-op is keen to support schemes to combat this both locally and nationally. "

Inspector Steve Curry said extra patrols were set up in east Brighton over the summer to tackle antisocial behaviour hotspots identified by community local action teams.

Overall crime in east Brighton is down 11 per cent but Mr Curry said gangs of youngsters, many under the influence of drink, were responsible for vandalism, graffiti and the intimidation of residents, especially the elderly.

He said: "Early intervention and stopping youngsters getting their hands on alcohol does reduce crime. Ordinary people care about this quality of life issue and deserve reassurance."

Parents have received letters from police telling them what their children have been up to and advising closer control.