More than 100 leading public health doctors and specialists from around the world have signed a letter to the director general of the World Health Organisation, Margaret Chan, calling for new controls on e-cigarettes and warning that they may be a stalking horse for the tobacco industry.

The experts want the WHO to bring e-cigarettes under the same tight controls as tobacco products, with bans on advertising and promotion. They say there is insufficient evidence so far that e-cigarettes are harmless and can help people to quit smoking.

Their biggest concern is that, if advertising and marketing are allowed, smoking will be "renormalised", undermining public smoking bans and undoing decades of effort to marginalise cigarettes and persuade people of the harm they do.

"By moving into the e-cigarette market, the tobacco industry is only maintaining its predatory practices and increasing profits," says the letter. It says the WHO must not be misled by the industry's efforts to present itself as a partner, as it did with filters and "low-tar" cigarettes in the past before scientists showed that those things did not reduce harm.

"If the tobacco industry were committed to reducing the harm caused by tobacco use, it would announce target dates to stop manufacturing, marketing and selling its more harmful products rather than simply adding e-cigarettes to its product mix and rapidly taking over the e-cigarette market.

"It would also immediately desist from its aggressive opposition to tobacco control policies such as tax increases, graphic health warnings and plain packaging," says the letter, whose signatories include Prof John Ashton, president of the UK Faculty of Public Health (FPH); Prof Rifat Atun, of the Harvard School of Public Health; and Prof Robert Beaglehole, of the University of Auckland.

Supporting the public health doctors are experts in paediatrics and cardiovascular disease, including Dr Hilary Cass, from Guy's and St Thomas' NHS trust in London, and Prof Helmut Gohlke, of the German Cardiac Society. Other signatories include Dr Jay Berkelhamer, of Emory University School of Medicine in the US, and Prof Frank Chaloupka, director of the Health Policy Centre at the University of Illinois.

The issue is controversial even within the public health community. This month, 53 scientists who take a different view wrote to Chan (pdf), saying that regulating e-cigarettes in the same way as tobacco products would cost lives by reducing the number of people using them to quit smoking.

"These products could be among the most significant health innovations of the 21st century – perhaps saving hundreds of millions of lives. The urge to control and suppress them as tobacco products should be resisted," they wrote.

But Simon Capewell, professor of clinical epidemiology at Liverpool University, speaking on behalf of the FPH, said its members were worried by the boom in e-cigarette use and the possible commercial interests behind it.

"The FPH is deeply concerned about the superficial analysis of e-cigarettes and that the potential harms of e-cigarettes have been systematically underestimated," he said. "The faculty is also concerned that the tobacco industry is cynically using discussions around e-cigarettes to undermine successful tobacco controls."

He said the industry was claiming e-cigarettes were solely a device to help people stop smoking, but the addition of flavours such as strawberry and bubblegum to the nicotine vapour suggested children were being targeted. It was possible that they might help some people to quit, but more evidence was needed, he said. "From the faculty's point of view, that is the single possible value they might have."

Prof Robert West, from University College London, whose recent study showed e-cigarettes were more effective than nicotine replacement therapy at helping people stop smoking, was a signatory to the earlier letter asking the WHO not to clamp down.

"The reason I was keen to join in with the original letter is that whatever policies are recommended by WHO or anyone else, the crucial thing is they should be based on a dispassionate evaluation of the evidence and what is worrying is that that is not what they are getting," he said.

He felt, however, that concern about the tobacco industry's involvement was valid. "That is a perfectly legitimate argument as long as no one is trying to pull the wool over anyone's eyes," he said.