The sharp increase in the use of e-cigarettes has not led more British children to take up cigarettes or regard smoking as normal, the first study of its kind has shown.

Some health experts and anti-smoking groups have expressed concern that the growth of e-cigarettes might normalise the idea of smoking for young people.

But the study led by Cardiff University researchers suggests the number of teenagers who said they had tried smoking or thought it was acceptable to smoke has continued to fall despite the rise in e-cigarette use.