Although he knew the habit was behind his recurring lung infections, the cigarette provided a moment of relaxation that was near impossible to give up.

Last year, struck down with serious chest pain and unable to smoke, Mr Stephens tried an e-cigarette instead.

Unlike other quitting attempts, the device enabled him to keep up his morning ritual and he hasn't smoked since.

Mr Stephens, 56, reports improved health, without the usual weight gain or anxiety.

"It's replaced all the ritualistic times I used to smoke," he said.

"I haven't had to change much swapping to vaping. When I used to try and give up smoking, it felt like something was missing."

Although Mr Stephens is one of many Australians who say they have quit smoking using nicotine contained in e-cigarettes, Australia is one of the only developed countries in the world that hasn't moved to legalise them.

It's legal to buy and sell e-cigarette devices, but you need to import the liquid nicotine to put inside them.

The situation has prompted a group of leading health experts to slam the Therapeutic Goods Administration, which they say has exaggerated e-cigarettes' dangers, while ignoring their "substantial" health benefits.

The group of 16 academics, researchers and doctors supported an application to the TGA to allow the use of nicotine at concentrations of 3.6 per cent or less for use in e-cigarettes as a tobacco harm reduction measure.

However, the TGA made an interim decision in February to continue its ban on nicotine for use in e-cigarette. It is due to make a final decision on March 23.

In response, the group has made a submission calling the ban "unethical" and "unscientific".

It has pointed out what it believes are "fundamental flaws" in the TGA's reasoning, which they say is not supported by evidence or overseas experience.

These include ignoring e-cigarettes' potential to aid quitting, and exaggerating the risk of increasing nicotine dependence as most users were smokers first.

A major concern for the TGA is that e-cigarettes could provide a gateway for young people to take up smoking, but the group says this is "unjustified and overblown" as overseas experience shows the opposite - that they are vaping instead.

The group points to 2014 research that estimated six million Europeans had quit smoking with e-cigarettes and a review that found vaping was at least 95 per cent safer than smoking.

Ideology was behind the ban and why Australia's most prominent health organisations, such as the Cancer Council and Heart Foundation, supported it, University of New South Wales Associate Professor Colin Mendelsohn said.

"It's political, it's emotional, it's ideological - it's we've always done it this way," he said.

"They are finding little problems in the research and are basically throwing smokers under the bus."

Australia was pursuing a "smoke-free agenda ... but like the war on drugs, prohibition doesn't work", Associate Professor Mendelsohn said.

He said some health advocates were "blinded by their hatred" of the tobacco industry, which was funding e-cigarette research and investing in e-cigarette companies.

"If they change over to a safer product, that's win for everyone," he said.

"They can save their businesses, keep their shareholders happy, but also billions of lives are saved."

With the UK, EU, US, Canada and NZ having either legalised e-cigarettes or are in the process of doing so, Associate Professor Mendelsohn said Australia was falling behind.

"It's extraordinary they exempt the most lethal consumer product ever invented, but they criminalise people who want to use low concentration nicotine in e-cig for harm reduction," he said.

"Nicotine is not the harmful ingredient in tobacco. It does not cause cancer or lung disease and has only minor effects on the cardiovascular system."

Another member of the group, Professor Ron Borland, who is also a fellow at the Cancer Council Victoria, said the council supported the ban as it was being cautious about the potential long-term risks.

However, he said he didn't support a ban on a product that had been found to prevent disease now because of potential problems in the future.

A TGA spokeswoman confirmed it was taking a "cautionary approach" to e-cigarettes.

"[There is ] limited evidence on their quality, safety, efficacy for smoking cessation or harm reduction, and the potential risks they pose to population health," she said.

She noted a World Health Organisation paper presented at a tobacco control conference in November last year that also urged caution.

Mr Stephens, who had read up on the evidence supporting e-cigarettes, questioned why a method that could help smokers and ease the burden on the health system was being ignored.

"I feel so much better," he said. "I have no desire to smoke at all."