Smokers trying to quit are 60% more likely to report success if they switch to e-cigarettes than if they use nicotine patches or gum, or try to use just willpower, according to new UK research.

The research contradicts a recent US study which cast some doubt on e-cigarettes' efficacy as a smoking cessation aid, and said they should only be used where all other therapies have failed.

The new UK study of nearly 6,000 smokers over a five-year period indicates that e-cigarettes could play an important role in reducing smoking rates and hence cutting tobacco-related deaths and illnesses.

Those studied had attempted to stop smoking without the aid of prescription medicine or professional support.

"E-cigarettes could substantially improve public health because of their widespread appeal and the huge health gains associated with stopping smoking," according to Dr Robert West of University College London, who headed the study.

The results showed that one-in five people trying to quit tobacco by using e-cigarettes reported that they had stopped smoking conventional cigarettes.

The results were adjusted for a range of factors that might influence success at quitting including age, nicotine dependence, previous attempts to give up smoking, and whether quitting was a gradual or abrupt process.

That compared with just 10% of those using over-the-counter products such as nicotine replacement patches or gum. Of those using their own willpower to quit, 15.4 percent had succeeded in stopping smoking.

The study is published in the journal Addiction.

E-cigarettes contain nicotine delivering it in a water vapour rather than in smoke from burning tobacco.

There has been an ongoing debate over the safety of e-cigarettes and their efficacy as a quit smoking method.

A US study published earlier this month by the Center for Tobacco Research and Education in California, said in cases where other smoking cessation methods had failed, doctors should support patients who wish to use e-cigarettes to quit smoking in these circumstances.

However, it says patients should be informed that while the e-cigarette aerosol is likely to be much less toxic than cigarette smoking, the products are unregulated, contain toxic chemicals and have not been proven as cessation devices.

This review of research to date on e-cigarettes said while data were limited, it is clear that e-cigarette emissions were not merely 'harmless water vapour' and could be a source of indoor air pollution.

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