Asda is raising the age for buying cigarettes in its stores to 18, the supermarket chain announced today.
Staff will ask customers who look under 21 to prove their age before selling them tobacco.
The decision to raise the minimum age from 16 follows the launch of a Department of Health consultation on the issue.
Asda will also raise the age for buying knives in its stores to 18. Both initiatives come into force on September 1.
The Challenge 21 scheme already operates across several supermarket chains in relation to sales of alcohol, fireworks and 18 rated DVDs and computer games.
Asda's retail director Andy Clarke said it was extending the policy to knives and cigarettes in response to changing public attitudes.
"By raising the age limit to 18 for the sale of cigarettes and knives, not only are we helping discourage teenage smoking but also helping our colleagues who sometimes find it hard to judge how old customers are."
The chain is calling on other retailers to follow its lead by increasing the minimum age for both tobacco.
The Violent Crime Reduction Bill, which bans all retailers from selling knives to under 18s, is expected to become law by the end of this year, subject to parliamentary approval.
Notices will appear in more than 300 Asda stores warning customers of its policy changes.
Ian Willmore, spokesman for anti-smoking group ASH, welcomed the move.
"We hope this will set an example to all retailers. Smoking is a lethal addiction that should not be promoted to children and retailers should make sure that cigarette sales on their premises are made to adults only," he said.
The DoH consultation is looking at whether the age limit for tobacco sales should be raised by one year or two - or stay at 16.
Respondents have until early October to say whether tobacco should be put on the same footing as alcohol.
Powers to raise the age - set at 16 since 1908 - were contained in this year's Health Act.
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