Teenagers who use e-cigarettes are more likely to take up smoking a year later, according to research.

A study in the journal Tobacco Control revealed youths who who tried e-cigarettes after never smoking before were almost three times more likely to go on to smoke cigarettes a year later than those who had never had an e-cigarette.

The research has led to calls for "policy discussions" around the sale of vaping products to under-18s.

The Scottish Government has already proposed a ban on selling e-cigarettes to under-18s in its Health Bill currently going through parliament a move that would bring Scotland into line with England.

Figures from ASH Scotland show that an estimated 5 per cent of adults in Scotland use e-cigarettes, however relatively few young people use them on an ongoing basis.

A 2015 survey of high school aged children in Scotland revealed that 12 per cent had tried them at least once, but just 2 per cent used them once a week ore more.

The recent study on teenagers and e-cigarettes looked at youngsters living in Hawaii, with an average age of just under 15 years.

Of those who had never smoked e-cigarettes or tobacco at the start of the study, one in 10 had tried e-cigarettes a year later, while 2% had experimented with cigarettes.

Further analysis showed only those teenagers who used a high number of e-cigarettes in 2013 were classed as "regular" smokers of cigarettes a year later.

The report authors said: "This suggests that e-cigarette use among adolescents is not without behavioural costs.

"These findings should be considered for policy discussions about the availability of e-cigarettes to adolescents."

The study also revealed that just under a third (31%) of the 2,300 students looked at had used e-cigarettes when they were first questioned in 2013. A year later, this figure had risen to 38%.

Most (98%) of those questioned had heard of e-cigarettes, and more than two-thirds (68%) considered them to be healthier than smoking.

The findings came as charity Cancer Research UK said the UK Government should make the tobacco industry pay for the damage it causes.

It said cuts to public health funding mean local stop smoking services are closing, but industry should "cough up" for such services.

By charging tobacco firms around 1p per cigarette sold in the UK, an extra £500m could be raised, it said.

According to Cancer Research UK's analysis, smoking continues to kill more than 100,000 people in the UK every year.

The tobacco industry makes a profit of more than £4,000 for every UK death caused by tobacco.

Internationally, it makes around £30 billion in profit.

Alison Cox, Cancer Research UK's director of cancer prevention, said: "For too long the tobacco industry has had an easy ride, making money without having to spend a single pound on the damage its products cause.

"It continues to profit from selling a highly addictive and lethal product that causes illness and death. Tobacco companies make billions of pounds every year, so we'd like to see them using their profits to keep stop smoking services open and fund advertising campaigns to help people quit.

"At a time when health budgets are stretched, this is a simple solution to a lethal problem. We urge the Government to make the industry cough up."

The Health (Tobacco, Nicotine etc. and Care) (Scotland) Bill has passed stage one of the parliamentary process and will be looked at again next month.

Public health minister Maureen Watt said: "This government is not opposed to e-cigarettes but we think it is right to protect children from nicotine addiction, and to limit the prevalence of smoking behaviours.

"Through this Bill, we will seek to strike that balance."