Electronic cigarettes - that contain nicotine-infused water which is inhaled as a vapour - face a crackdown in Britain after the health minister said some were found to pose a potential danger.
According to The Sun, around two million people in the country have tried them, and 650,000 use them regularly.
Health Minister Simon Burns said some e-cigarettes have been "found to pose a potential danger".
A consultation has found support for having the e-cigarettes controlled by the Medicines and Healthcare Regulatory Authority (MHRA).
"It's illegal to sell e-cigarettes as a 'quit smoking' aid unless they're licensed as a medicine," the MHRA said.
Shadow health minister Diane Abbott said the potential of e-cigarettes to help Britain's 10 million smokers quit is being held back by a "lack of scientific research" into them.