The one-month pilot includes stores in and around Doncaster in South Yorkshire, and Cleethorpes, Ashby and Crowle in Lincolnshire.
S taff will ask for ID from consumers buying age-restricted products - including alcohol - if they look under 30. A Tesco spokesman said the scheme was a local initiative rather a head office decision. "We support the decision that the management have taken locally," he said.
He added: "If it proves popular with customers it may be something we'll take further, but if no one likes it we'll react to that. We need to support our staff because they are put in difficult situations," he said.
When asked whether the approach would have an adverse effect on sales, the spokesman replied: "Not necessarily . It may just encourage local customers to make sure they have the correct ID on them."
Asda is currently trialling a Challenge 25 scheme in 10 of its Scottish stores, but the Retail of Alcohol Standards Group still supports Challenge 21 for most retailers.
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