Smokers should be encouraged to try e-cigarettes to help them quit, according to a review from Britain's top public health body that is the latest salvo in the increasingly politicised debate over e-cigarettes.

Australia's top smoking experts have rejected the report, saying it displays "naive optimism" and is based on flawed research. They say the proponents of so-called "vaping" are treating e-cigarettes as if they are more beneficial than other quit-smoking treatments despite little evidence they are, and some evidence they could even be worse.

A demonstration of an e-cigarette. Credit:AP

The debate over e-cigarettes has become so bitter in part because of the high stakes. Tobacco is an incredibly dangerous drug – it kills half of all people who use it. Most experts are pretty clear e-cigarettes are not going to be anywhere near as dangerous as that.

But whether or not e-cigarettes are an important tool to help people quit, and whether they should face the same requirements as other quit-smoking drugs to prove their safety and efficacy, is where it starts getting messy.