The proportion of supermarkets selling alcohol to children increased this summer despite Government crackdowns, figures have shown.
Ministers said they were disappointed with results of the alcohol misuse enforcement campaign and warned the licensed trade that they expected "real improvements".
Kwik Save was the worst-performing chain with a 26% failure rate, followed by Somerfield with 22% and Sainsburys and Morrisons, both with 20%.
Out of 1,346 "stings" carried out at supermarkets, children were able to buy alcohol in 244 cases.
Overall, supermarkets' failure rate was 18% compared with 17% in the previous Home Office campaign.
In pubs and bars, one in three children (29%) was able to buy alcohol in test purchases, while in the whole off-licence trade, including supermarkets, the figure was 21%.
Results showed widespread variations across England and Wales, with pubs and bars in Wales breaking the law most frequently, selling to children in 48% of cases.
It was followed by the East of England with 39%. The North East had the best results - just 18%.
In all, police summonsed 892 licensees during the month-long campaign, 780 for selling to minors.
Home Office minister Vernon Coaker said: "I am disappointed with these test purchase results. The problem of alcohol-fuelled crime and disorder is an issue of major public concern and we are all responsible for tackling it."
