In the Forest division a 15-year-old girl was sold alcohol in four out of 13 off-licences. In Gloucester a similar girl was served in three out of 12.

The joint operation aims to crack down on binge drinking, underage drinking and anti-social behaviour.

The seven premises that failed the "test" now face possible prosecution.

A police spokesman said selling alcohol to the under 18s would not be tolerated.

"The spot-checks will continue to be carried out on a random basis to ensure that young people are not able to purchase alcohol in this way, he said.