Electronic cigarettes contain carcinogenic chemicals that make some as harmful as normal tobacco, a new French study has claimed.
The report comes after government plans announced in May this year to ban electronic cigarettes from public places in France.
Now monthly magazine 60 Millions Consommateurs (60 Million Consumers) has branded the devices as "far from the harmless gadgets they're sold as by manufacturers".
The magazine - which reports the findings of the National Consumers' Institute - said it tested ten different rechargable and disposable models for carcenogenic and toxic properties.
Editor Thomas Laurenceau wrote: "We detected a significant quantity of carcinogenic molecules in the vapour of these cigarettes which have thus far gone undetected.
"In three models out of ten the levels of the carcinogenic compound formaldehyde come close to those of a conventional cigarette.
"The highly toxic molecule acrolein was also detected in the vapours of e-cigarettes, sometimes at levels even higher than in traditional cigarettes."
The report also criticised certain models for lacking child-proof safety caps because nicotine levels contained in the liquid content of an electronic cigarette could be lethal to children.
Mr Laurenceau added: "It's not a reason to ban them, but a good reason to control them."
Toxic levels of various molecules were found in some of the e-cigarettes meaning they could be just as dangerous as traditional cigarettes. Image shows lung cancer cells
Toxic levels of various molecules were found in some of the e-cigarettes meaning they could be just as dangerous as traditional cigarettes.
French Health Minister Marisol Touraine announced in May that the ban on smoking in public places would be extended to cover electronic cigarettes, and that they would be subject to the same controls as tobacco.
The move has sparked outrage among sellers and users of the battery-powered devices which contain liquid nicotine that is turned into a vapor when inhaled.
Ms Touraine said: "The e-cigarette is not an ordinary product.
"We need to apply the same measures as there are for tobacco.
"That means making sure it cannot be smoked in public places, that its sale is restricted to over 18s and that firms are not allowed to advertise the products."
E-cigarettes are currently legal to use in bars and restaurants and all other public places, where traditional smoking has been banned.
A ban would harm the booming e-cigarette industry in France, where around one million people now use the gadgets, vendors insist.
E-cigarettes were first invented in China in 2003, as many nations began imposing bans on smoking, and are aimed at giving the user a similar sensation to smoking a cigarette.
In March this year, health expert Professor Bertrand Dauzenberg told France's Europe 1 radio that e-cigarettes could have the opposite effect that is designed for.
"These electronic cigarettes could also lead children to start smoking and sale should be banned to minors.
"However for heavy smokers, I believe these will reduce the health risks, but the best way to quit smoking is the patch or chewing gum."
- DAILY MAIL