Police and Trading Standards officers have said they are disappointed after six premises sold alcohol to underage teenagers during a test purchase operation in Bristol.

Officers and volunteers, aged 16, visited nine premises and attempted to buy alcohol in city centre pubs and nightclubs over recent weekends.

Sharon Sawyers, Trading Standards lead officer said: "These are very disappointing results which show that there is much more work to be done to ensure that city centre pubs and clubs are observing the law and the terms of their licences by taking adequate steps to ensure that they are not selling alcohol to young people under eighteen."

Councillor Derek Pickup said the city council was determined to ensure that licensed premises do not allow under age drinking and further operations are planned to take place throughout 2009.

He added: "Under age drinking is not acceptable in Bristol and contributes to anti-social behaviour by young people.

"It is essential that licensee's keep within the terms of their license or their licence will be reviewed which could lead to it being revoked."

On one purchasing exersise, the team was accompanied by Councillor Alex Woodman, who sits on the City Council's Licensing Committee.

Councillor Woodman said: "Preventing underage and irresponsible drinking is an important part of making our city centre a safe and enjoyable place to visit.

"I was sad to see so many premises breaking the law by serving to people under eighteen, and not taking simple steps to check the age of their customers."

Sergeant Stephen Bell, of Avon and Somerset police, said: "We are disappointed by the results of the operation and will continue to work in partnership with the council and the licensing trade to ensure that robust measures are in place to prevent under age entry and service at premises within the city centre."