Electronic cigarettes should be banned from indoor spaces and face curbs on their sale over health fears, the World Health Organisation has said.

Despite releasing vapour instead of smoke the devices, officially known as electronic nicotine delivery systems (ENDS), still carry a risk to those standing around users, a report for the Geneva-based UN organisation said.

In a report it said: "The fact that ENDS exhaled aerosol contains on average lower levels of toxicants than the emissions from combusted tobacco does not mean that these levels are acceptable to involuntarily exposed bystanders.

"In fact, exhaled aerosol is likely to increase above background levels the risk of disease to bystanders, especially in the case of some ENDS that produce toxicant levels in the range of that produced by some cigarettes."

The report, to be discussed at October's WHO Framework Convention on Tobacco Control in Moscow, also recommends preventing manufacturers from marketing e-cigs as "smoking cessation aids" until they provide scientific evidence to back the claim.

The report also says that they should be banned from sale to minors, and that vending machines should be removed "in almost all locations".

Electronic cigarettes are currently regulated as consumer products in the UK but last year the Medicines and Healthcare Products Regulatory Agency announced that nicotine-containing products (NCPs), including some e-cigs, are to be regulated as medicines to make the products more "safe and effective", the move coming into effect in 2016.