Electronic cigarettes and similar devices are dangerous to health and must be regulated to curb the tobacco industry's tactics to get young people hooked on nicotine, the World Health Organization warned Tuesday.

"Nicotine is highly addictive. Electronic nicotine delivery systems (ENDS) are harmful, and must be better regulated," said WHO chief Tedros Adhanom Ghebreyesus.

The WHO Report on the Global Tobacco Epidemic 2021, which focused on new and emerging products, was published on Tuesday and said ENDS should be tightly regulated for maximum public health protection.

"Where they are not banned, governments should adopt appropriate policies to protect their populations from the harms of ENDS, and to prevent their uptake by children, adolescents and other vulnerable groups," Tedros said.

The UN health agency's eighth annual report said ENDS manufacturers often target youths with thousands of tantalising flavours -- the document listed 16,000 -- and reassuring statements.

Former New York mayor Michael Bloomberg, the WHO's global ambassador for non-communicable diseases, said there were still more than a billion smokers around the world.

"As cigarette sales have fallen, tobacco companies have been aggressively marketing new products -- like e-cigarettes and heated-tobacco products -- and lobbied governments to limit their regulation," he said.

"Their goal is simple: to hook another generation on nicotine. We can't let that happen."

Concern for youngsters 

The UN health agency is particularly concerned by people under 20 using e-cigarettes due to the harmful effects of nicotine on brain development.

The WHO also believes that children who use these devices are more likely to smoke later in life.

However, regulating such products is not necessarily straightforward because the product range is very diverse and rapidly evolving, said Ruediger Krech, director of the WHO's health promotion department.

"Distinguishing the nicotine-containing products from the non-nicotine, or even from some tobacco-containing products, can be almost impossible. This is just one way the industry subverts and undermines tobacco control measures," he said.

The WHO recommends that governments do whatever they can to prevent non-smokers from taking up e-cigarettes, for fear of "renormalising smoking in society".

The report found that 32 countries have banned the sale of ENDS.

A further 79 have adopted at least one partial measure to either prohibit the use of such products in public places, prohibit their advertising, promotion and sponsorship or require the display of health warnings on packaging.

"This still leaves 84 countries where they are not regulated or restricted in any way," the WHO said.

The Geneva-based organisation stressed that efforts to regulate e-cigarettes should not distract from the fight against smoking.

Though the proportion of smokers has fallen in many countries, population growth means that the total number of smokers remains "stubbornly high," the WHO said.

"Tobacco is responsible for the death of eight million people a year, including one million from second-hand smoke," it stressed.