Unlike proposed new laws in Scotland, the ban will be voluntary, but councillors hope it will be enough to reduce public disorder in the borough.
Croydon councillor Steve O’Connell was reported by the London Evening Standard as saying: “We want to tackle the corner shops that are selling eight cans of Stella for a fiver because it can lead to young people getting involved in anti-social behaviour.”
The scheme was backed by London Mayor Boris Johnson, who told the capital’s assembly the idea was “a very interesting one”.
He added: “Where we have got particular problems in particular areas, off-licences and supermarkets should stop the sale of alcohol to the under-21s.
“It is something where the boroughs can take a lead and banish the scourge of binge drinking.”