The health benefits of e-cigarettes have been at the centre of debate for some time.
Now, experts have said that despite them not being "absolutely safe", e-cigarettes have the potential to contribute to reducing death and disability caused by Britain’s biggest killer - smoking.
Writing in the British Medical Journal (BMJ), they said: "E-cigarettes represent an important means to reduce the harm to individuals and society from tobacco use.
"They should continue to be supported by government and promoted as a tobacco harm reduction strategy."
Experts reviewed a new report by the Royal College of Physicians (RCP) on the role of e-cigarettes in tobacco harm reduction.
They argued that e-cigarettes and other non-tobacco nicotine products "offer the potential to radically reduce harm from smoking in our society".
"This is an opportunity that should be managed, and taken," they said.
Despite declining prevalence over recent decades, there are still nearly nine million smokers in the UK and a high proportion of them are among the most disadvantaged in our society.
Smoking is also still the largest avoidable cause of premature death, disability and social inequalities in health in the UK.
Experts said that, even at the doses absorbed from cigarettes, nicotine causes little if any harm. It is the carcinogens, carbon monoxide and thousands of other toxins in tobacco smoke that kill.
This means that health harms from smoking can be avoided by substituting cigarettes with a less toxic source of nicotine.
Researchers said the emergence of e-cigarettes has "revolutionised" the choice of nicotine products available to smokers.
An estimated 2.6 million people currently use e-cigarettes in the UK, almost all of them are or have been smokers, and one third of them no longer smoke.
As more and more people have taken to using them, there have been various health concerns raised.
Some people thought they might attract young people to become smokers. Others thought it would re-establish the act of inhaling nicotine as something that's acceptable in public.
It was also thought that e-cigarettes would divert smokers who wanted to quit away from other treatment services.
The new report argues that, while not "absolutely safe", the hazard to health arising from long term vapour inhalation from e-cigarettes is unlikely to exceed 5% of the harm from smoking tobacco.
The report finds that among adults in the UK, e-cigarette use is almost entirely limited to those who are or have been smokers, in most cases as a means to cut down or quit smoking.
It also finds no grounds to suspect that use of e-cigarettes renormalises smoking, or that use where smoking is prohibited represents a significant hazard to health.
It concludes that the availability of e-cigarettes is unlikely to account for the recent decline in number of smokers accessing stop smoking services.
The report recognises that tobacco industry acquisition of many formerly independent e-cigarette producers and importers is a cause for concern.
But it says that advertising restrictions due to be implemented in May 2016 "go some way towards alleviating these concerns".
Health experts concluded that e-cigarettes have so far been beneficial to UK public health, both at individual and population level, by providing smokers with a viable alternative to tobacco smoking.