The legal age for buying tobacco is to be raised from 16 to 18, the Government has announced.
The Public Health minister Caroline Flint said the new law would come into effect from 1 October.
Campaigners welcomed the move, following a public consultation last July, but raised concerns over how the law would be enforced.
Government statistics show that 9 per cent of children aged between 11 and 15 smoke - down from 13 per cent in 1996. But ministers want to drive the figure down further and believe that raising the limit will make it easier for retailers to spot under-age smokers.
England and Wales will now move into line with Canada, Australia, New Zealand and the US. A ban on smoking in enclosed public places comes into effect on 1 July but NHS and government buildings will be smoke-free from today.
Ms Flint said: "Smoking is dangerous at any age, but the younger people start, the more likely they are to become life-long smokers and to die early.
"Buying cigarettes has been too easy for under-16s. The law change demonstrates our determination to stop this and to reduce the number of teenagers who smoke.This, in turn, will reduce the number of people with preventable diseases and the incidence of health inequalities."
Only 23 per cent of under-16s who try to buy tobacco found it difficult to do so, according to a Department of Health study.
The Smoking, Drinking and Drug Use Among Young People in England Survey 2004 revealed that 70 per cent of 11 to 15-year-old smokers buy their cigarettes from small shops such as newsagents.
A spokeswoman for the British Medical Association said: "Young people, especially girls, still think it looks 'cool' to smoke. Films and celebrities perpetuate this image, and the BMA would like to see this tackled."
Deborah Arnott, director of the anti-smoking charity Ash, called for tougher sanctions for retailers who sold to children. "More needs to be done to enforce the penalties. The fines are pitiful. In 2004, only about 50 retailers were fined for selling to those under-age."