Anti-smoking campaigners in Bradford today welcomed new Government warnings about the health risks of fake cigarettes.

The alert was sounded over the contents of black-market cigarettes made mostly in China and Eastern Europe.

They may look identical to the real thing but contain more tar, nicotine and carcinogens.

Di Woodall, of the Bradford Stop Smoking group, said people think the contents are the same because they look alike. She said: "There is no such thing as a safe cigarette but people buying fakes do not realise the contents are not regulated. They believe they are the same as legitimate cigarettes. Tobacco is regulated to a certain amount but, when it isn't, who knows what is in them?"

The dangers were highlighted after a third of smokers admitted buying fake cigarettes despite a crackdown. Customs seized nine billion illicit cigarettes between 2000 and 2004 but the black market has exploded over two years. It is now worth £500 million and makes up 15 percent of the UK market.

Independent research shows counterfeit cigarettes sold in Britain contain five times as much cadmium, six times as much lead and high levels of arsenic.

Di Woodall said: "Somebody always knows somebody. They look like bona fide cigarettes but they do not have the tax symbol on them. People should be aware of the difference in content."

Customs Minister John Healey said 85 percent of cheap cigarettes sold illegally in London and more than half of all smuggled cigarettes seized nationally are fake. On average more than a million are seized in the UK daily, but the Government says the public are unaware of the problem and the risks.

A third of UK smokers say they sometimes buy fakes but only one in five know they are smuggled. And in London, where 85 per cent of cigarettes sold on the streets are fake, two-thirds of smokers mistakenly believe they are real.