A rise in the use of electronic cigarettes among American adults is linked to a significant increase in the numbers of people quitting smoking, researchers said on Wednesday.

In a study published in the BMJ British medical journal, scientists from California said their findings were based on the largest representative sample of e-cigarette users to date and provided a "strong case" that e-cigarettes have helped to increase rates of smoking cessation.

"These findings need to be weighed carefully in regulatory policy making and in the planning of tobacco control interventions," the researchers, led by Shu-Hong Zhu at the University of California, said in their study.

The global scientific community is divided over e-cigarettes and whether they are a useful public health tool as a nicotine replacement therapy or a potential "gateway" for young people to move on to start smoking tobacco.

Many specialists, including health experts at Public Health England, think e-cigarettes, which contain nicotine but no tobacco, are a lower-risk alternative to smoking.

But the U.S. surgeon general last year urged lawmakers to impose price and tax policies that would discourage their use.

Zhu's study used five U.S. population surveys dating from 2001 to 2015. E-cigarette users were identified from the most recent survey in 2014/15, and smoking quit rates were obtained from those who had reported smoking cigarettes 12 months before the survey. Rates were then compared to four earlier surveys.

The results showed that e-cigarette users were more likely than non-users to make a quit attempt (65 percent versus 40 percent) and more likely to succeed in quitting smoking tobacco for at least three months.

The overall population quit rate for 2014/15 was 5.6 percent, up from 4.5 percent in 2010/11, and higher than the rates in all other survey years.

The researchers said that while the 1.1 percentage point rise in the smoking cessation seemed small, it represented around 350,000 additional U.S. smokers who quit in 2014/15.

"Other interventions that occurred concurrently, such as a national campaign showing evocative ads that highlight the serious health consequences of tobacco use, most likely played a role in increasing the cessation rate," Zhu said.

"But this analysis presents a strong case that e-cigarette use also played an important role."

Jamie Hartmann-Boyce, an expert at Britain's Oxford University and at the Cochrane Tobacco Addiction Group who was not involved in the BMJ research, said the findings suggested e-cigarettes may prove a useful tool in bringing tobacco use down.

"Findings from this study are promising and are consistent with a growing body of evidence ... that electronic cigarettes with nicotine may help people stop smoking," she said.