Serve Legal, which carries out test purchasing for retailers and other businesses, polled more than 300 young people aged 18 and 19 about how under-age drinkers get hold of alcohol.
Two-thirds said older family members or friends are buying alcohol for under-18s. Ninety-five per cent said under-age drinkers would try to obtain alcohol from their parents with their knowledge and consent, up 10% from the year before, while 86% said they would ask siblings or friends to proxy purchase for them.
Just 4% said youngsters would try to buy alcohol from supermarkets, compared with 63% from small local convenience stores and 58% from pubs.
More than 80% of those polled said under-18s would probably or definitely not succeed in buying alcohol from supermarkets, up from 72% in 2008.
Serve Legal director Charlie Mowat said: “Our research is probably the most revealing study in the area of under-age alcohol consumption as it was carried about by young people who have purchased alcohol themselves or know what their friends are doing.”
Asda external affairs and corporate responsibility director Paul Kelly said: “At Asda our customers are our absolute priority and that is why we have introduced and enforce the Challenge 25 policy and also refuse to serve over-18s where we believe the customer is making a proxy purchase.
“The fact that proxy purchasing is on the rise, with under-18s getting access to alcohol through friends and family members, is a worrying trend and reinforces the notion that everybody in society needs to play a role in protecting young people from alcohol.”
Drinkaware chief executive Chris Sorek said: “This new research reinforces our findings that families are the main dealers of alcohol to 15 to 17-year-olds.”
He added: “Evidence shows that young people who drink from an early age are more likely to drink more, and more frequently, than those who delay their first drink.
“Although parents might feel under pressure to allow their children to drink, they should remember that if they give their children alcohol, they are inadvertently putting them at risk.”