Promotion of e-cigarettes needs to be considered "carefully", experts have said after finding that if teenagers notice the products in shops it may influence whether or not they use them.

Officials must consider the balance between promoting e-cigarettes to adult smokers to help them quit and minimising their uptake by teens, they said.

Researchers from the University of Stirling studied almost 4,000 Scottish teens to examine whether there was a relationship between adolescents' recollection of e-cigarette displays at point of sale (POS) and their past use and intended use of the products.

Their study, published in the journal BMC Public Health, found that teens who had recalled seeing e-cigarettes for sale in small shops or supermarkets were more likely to intend to try them in the next six months than those who did not remember.

And young people who recalled seeing e-cigarettes in small shops were more likely to have used the products in the past.

"Given that our study found an association between POS exposure to e-cigarettes and both their use and intention to use in young people, policymakers in the EU and elsewhere need to consider very carefully how to balance the promotion of e-cigarettes to adult smokers as an aid to help them quit, while at the same time minimising their uptake by young people," corresponding author Catherine Best said.

Commenting on the study, Paul Aveyard, professor of behavioural medicine at the University of Oxford, said: "The authors found that young people who recalled e-cigarette advertising were more likely to intend to use e-cigarettes in the future and suggest this could be because the advertising prompts them to intend to do so.

"However, an obvious explanation is that people with no interest in smoking or e-cigarettes will tend not to notice them on display, whereas those who do will notice them.

"We look at what we are interested in and this is the most likely explanation of the study's findings."