More than half of the shops tested for under-age sales failed, according to a new report.
Brighton and Hove City Council’s annual licensing report said that three out of six off-licences tested last November and three out of five shops tested in January sold alcohol to under 18s.
Council licensing officials and Sussex Police carry out regular checks, sending under-age volunteers into shops to try to buy drink.
The report was presented to the council’s Licensing Committee at Hove Town Hall on 29 June.
Labour councillor Joy Robinson said: “A 50 per cent failure rate doesn’t look particularly good to me.
“It suggests perhaps we ought to be doing more testing but I understand there could be budget constraints.”
Another Labour councillor, Emma Daniel, who chairs the Licensing Committee, asked whether businesses were targeted because they were believed to be likely to sell to under 18s.
And fellow Labour councillor Tobias Sheard asked whether the percentage of businesses failing the test was down to better intelligence or “the luck of the draw”.
Council licensing officer Sarah Cornell said that businesses were targeted based on intelligence, adding that the council offered pub and off-licence staff training in how to combat under-age sales.
As a result of the failed test purchases, two licensing reviews were carried out this year because two businesses failed more than one test.
Inspector Mark Redbourn, from Sussex Police, said: “We would focus on areas where we are receiving reports of anti-social behaviour with young people involved with alcohol.
“That drives the areas we target, so it’s not a surprise there’s a high percentage of failure.
“We don’t work from one single strand of intel. We work from multiple, so we are fairly confident that a premises is involved or failing in that area.”
Premier Express Bevendean Convenience Store received a “yellow card” warning after its licence was reviewed at a hearing in March after a failed test in January.
And Booze Corner, in Lewes Road, Brighton, had its licence revoked after a review last month after a failed test on the same day in January as the Bevendean store.
