NEARLY half a million people have switched smoking tobacco for e-cigarettes in the last year as they try to kick the habit, research shows.

Action on Smoking and Health (ASH) said there are now 2.6 million vapers in Britain, up from 2.1 million in 2014, with nearly all of this increase attributable to a rise in the number of ex-smokers using electronic cigarettes.

The campaign group said the figures showed the "value" of e-cigarettes in helping smokers give up tobacco but also warned of a "worrying" increase in people falsely believing they are as harmful as or even more dangerous, with nearly a quarter (22 per cent) believing this compared to 15 per cent last year.

ASH said analysis by researchers at King's College London shows that electronic cigarette use increased among ex-smokers from 4.5 per cent in 2014 to 6.7 per cent in 2015 but remained the same among current smokers at 17.6 per cent.

Vaping remains extremely rare amongst people who have never smoked, with just 0.2 per cent of users falling into this category over the last three years.

The most popular reason people gave for using e-cigarettes was to help them stop smoking completely (48 per cent) and to prevent them from relapsing to smoking (38 per cent).

Deborah Arnott, chief executive of ASH, said: "The number of ex-smokers who are staying off tobacco by using electronic cigarettes is growing, showing just what value they can have.

"But the number of people who wrongly believe that vaping is as harmful as smoking is worrying.

"The growth of this false perception risks discouraging many smokers from using electronic cigarettes to quit and keep them smoking instead which would be bad for their health and the health of those around them."

Dr Leonie Brose, of the Institute of Psychiatry, Psychology & Neuroscience at King's College London, said: "We must clearly communicate the relative safety of electronic cigarettes to smokers.

"The proven harm of tobacco is currently getting less coverage than the much smaller and far less certain harm from electronic cigarettes. We owe it to smokers to provide them with accurate information."