Australia must make it as easy as possible for smokers to get their hands on e-cigarettes, doctors and a giant tobacco company have told federal parliamentarians.

Doctors who've become advocates for drug law reform say Australia must not "sacrifice" smokers who can't quit by denying them a safer alternative.

They say Australia must follow the US and the UK and give smokers easy access to vastly less harmful e-cigarettes - or nicotine vaping products - so they can get their hit without the toxic smoke that does so much harm to the human body.

E-cigarette devices are legal in Australia but the sale and possession of the nicotine used in them is illegal.

Retired doctor Dr Alex Wodak, who now heads the Australian Drug Law Reform Foundation, has told a federal parliamentary committee that must change.

He cited a major study by a public health agency in England that found found e-cigarettes were about 95 per cent safer than combustible cigarettes.

Australia should facilitate easy access to a diverse range of products, such as flavoured nicotine liquids, that would appeal to smokers who want to quit, he said.

"It's very important, in harm reduction and public health generally, to have your intervention (be) attractive to the people most at risk," Dr Wodak said.

"I think having a vibrant vaping community network, through the distribution of vaping shops, is very important from a public health perspective."

Colin Mendelsohn is an Associate Professor in the School of Public Health and Community Medicine at the University of NSW. He's also a GP and tobacco treatment specialist who helps smokers quit.

He says Australia's policy focus on abstinence when it comes to smoking is naive in the face of another option: harm minimisation.

"The reality is that many smokers are unable or unwilling to quit. We can't just sacrifice them," Dr Mendelsohn told the committee.

The committing is hearing from experts about how the health risks of e-cigarettes and combustible products compare, and how such products should be regulated.

On Wednesday, it heard smoking rates had fallen in the e-cigarette-friendly UK and US, with one 2014 EU study finding that more than 6 million Europeans had quit tobacco with e-cigarettes.

It also heard that almost all e-cigarette users, or vapers, were former smokers, and there was no evidence that young people who'd not formerly smoked were suddenly turning to vaping.

In 2015, the first large-scale Australian study found two thirds of smoking Aussies would die from smoking-related diseases.

In February, Australia's medicines regulator, the Therapeutic Goods Administration, decided to maintain a ban on nicotine e-cigarettes, arguing they could have a negative impact on tobacco control and may "re-normalise" smoking.

But for traditional tobacco giant British American Tobacco - which is now making "smokeless" products - it's about building a new market which also happens to be safer.

"My company aims to become a leader in the market globally," the tobacco company's principal toxicologist for vaping products, Dr Sandra Costigan, told committee members.

She said the tobacco giant wasn't "keeping all our eggs in one basket ... the smoking basket".