LONDON (REUTERS) - An estimated 3.2 million people in Britain are now users of e-cigarettes, or vapes, compared with around 7.4 million who smoke tobacco cigarettes, according to data from a survey conducted by an anti-smoking charity.

Among those who vape, more than half are people who have switched to electronic cigarettes after quitting tobacco, the survey by Action on Smoking and Health (ASH) found, and 40 per cent are tobacco smokers trying to quit.

Experts at Public Health England say vaping is around 95 per cent less harmful than smoking tobacco cigarettes, and health authorities in Britain foresee substantial public health benefits if smokers are able to switch.

Internationally, however, the scientific community is divided over e-cigarettes as a nicotine replacement therapy. E-cigarettes have no tobacco, but contain nicotine-laced liquids that the user inhales in a vapour.

Deborah Arnott, ASH's chief executive, said the survey data showed British smokers are "getting the message on e-cigarettes" and switching to them as a healthier option.

The number of vapers in Britain has grown rapidly over the past few years - from around 700,000 in 2012 to more than 3 million now.