Dawn Primarolo, the public health minister, said: "It's vital we get across the message to children that smoking is bad. If that means stripping out vending machines or removing buy cigarettes from behind the counter, I'm willing to do that." According to the Office for National Statistics, the proportion of adults who smoke has dropped from 24 per cent to 22 per cent since the ban was introduced last July. The Government has a target of reducing the proportion of smokers to 21 per cent by 2010. David Cameron, the Conservative leader, said: "I think this is worth looking at. As someone who struggled with giving up smoking, it helps if you take away some of the temptation." Shane Brennan, a spokesman for the Association of Convenience Stores, which represents 33,000 shops, said: "This is going to be a massive burden on retailers and we are not sure that the end justifies the means. Cigarettes are already kept behind the counter."