More evidence has been uncovered, to suggest electronic cigarettes help smokers stop or reduce their smoking.

Researchers from New Zealand and the UK found around nine percent of smokers who used e-cigarettes were able to stop smoking within a year.

Of those who used a placebo, nicotine-free e-cigarette, around four percent stopped within the same timeframe.

The review found 36 percent of e-cigarette users who had not quit, halved the number of conventional cigarettes they smoked.

For placebo users, that figure was at 28 percent.

The Cochrane Review found that while e-cigarettes containing nicotine were more effective than those without it in helping smokers kick the habit, the results need to be confirmed by more studies.

E-cigarettes are available in New Zealand, but are not currently recommended for use by the Ministry of Health.