Health education workers have asked for guidelines on how much alcohol children can safely consume after a survey has shown an increase in under-age drinking.
The number of children who admit to drinking alcohol - more than 70 per cent of 14 and 15-year-old boys - has gone up by around 10 per cent since last year, according to the annual survey by the Schools Health Education Unit at Exeter University.
It shows that, by the age of 14, boys who admit to consuming alcohol drink the equivalent of five pints of beer a week on average, and girls an average of four pints.
This year's Exeter survey of more than 8,000 young people aged between 12 and 15 also fuels the controversy over alcopops, the alcohol-laced fruit drinks which the Government is considering banning. It shows that both boys and girls who drank alcopops consumed far more alcohol than the others.
The finding that many children drink at home with their parents' knowledge has led the researchers to suggest that parents may need advice. They point out that there are well-publicised limits for adults - no more than 21 units a week for women and 28 for men are recommended, a unit being equivalent to half a pint of beer or a glass of wine - but no similar advice for children.
John Balding, director of the study, said: "The negative outcomes of under-age drinking are horrendous . . . It would be enormously helpful to be given authoritative guidance on appropriate levels of drinking for different age groups."
The BMA is not prepared to say precisely how much alcohol children ought to be able to consume. But it wants the Government committee chaired by Health Secretary Jack Straw that is considering a ban on alcopops to take a fresh look at under-age drinking.
Dr Bill O'Neill, science and research adviser at the BMA, said: "It would be very difficult to come up with an amount of alcohol deemed to be safe because of the enormous variation in children's body size. And it would deflect from the real problem, which is about under-age sales and the promotion of alcohol among young people.
"There ought to be advice on sensible drinking and the context in which children are allowed to drink. Rigid guidelines would not be helpful."
In the survey about two-thirds of 12 and 13-year-olds said they drank at home and more than half of these said their parents knew.
Fewer than half the 14 and 15-year-old boys questioned said they had not had any alcoholic drinks in the week before the survey, compared to 59 per cent the year before.
* Young People and Alcohol: its use and abuse is published by the Schools Health Education Unit, University of Exeter, Pounds 17