Electronic cigarettes pose substantially less harm to smokers than tobacco, a report has concluded - despite an "increasingly common misconception" they are just as dangerous.

Although there is a possibility that e-cigarettes could cause some long-term harm, the UK's Royal College of Physicians (RCP) has said such devices have the potential to make a "major contribution" to preventing premature death and disease among smokers.

No evidence was found to suggest e-cigarettes are a "gateway to smoking" or normalise the habit - but experts agree they are beneficial for encouraging smokers to quit.

The report also stated "the public can be reassured that e-cigarettes are much safer than smoking".

Professor John Britton, who chairs the RCP's Tobacco Advisory Group, said: "The growing use of electronic cigarettes as a substitute for tobacco smoking has been a topic of great controversy, with much speculation over their potential risks and benefits.

"This report lays to rest almost all of the concerns over these products … Smokers should be reassured that these products can help them quit all tobacco use forever."

RCP president Professor Jane Dacre added there was an "opportunity to improve the lives of millions of people" if e-cigarettes are carefully managed and proportionately regulated.

Cancer Research UK has said e-cigarettes have "real promise in helping to reduce the huge death toll from tobacco" - and described the RCP's report as "an accurate summary of the latest scientific evidence on e-cigarettes".

The organisation's director of prevention, Alison Cox, added: We should grasp every opportunity to encourage as many people as possible to stop smoking for good."