New Delhi: Sections of consumers have decried a Union health ministry advisory that calls on states to ban the manufacture, trade and sale of electronic-cigarettes, e-nicotine-flavoured hookahs and similar products, saying such devices are less than harmful than cigarettes.

The ministry's advisory issued on Tuesday has pointed out that Bihar, Jammu and Kashmir, Karnataka, Kerala, Mizoram and Punjab had already prohibited the production, trade or sale of electronic nicotine delivery systems (ENDS) during 2016 and 2017 and urges other states to follow suit.

A consumer group called the Association of Vapers of India said on Wednesday it is opposed to the Centre's advisory because evidence available from multiple scientific institutions has indicated that e-cigarettes are substantially less harmful than combustible cigarettes.

A typical e-cigarette produces an aerosol by heating a liquid that contains nicotine - the addictive drug in regular cigarettes, cigars and other tobacco products - along with flavourings and other chemicals that help generate the aerosol, according to the US Centers for Disease Control.

"States and Union Territories are advised, in larger public health interest and in order to prevent the initiation of ENDS by non-smokers and youth... to ensure that any ENDS devices are "not sold, manufactured, distributed, traded, imported or advertised" in their jurisdictions, the health ministry advisory said.

The health ministry advisory has cited a World Health Organisation document that listed 30 countries, including Australia, Brazil and Singapore, that have banned ENDS.

But the AVI has pointed out that the same WHO document has also listed 65 countries that have regulated ENDS. These include the US, the UK and countries in the European Union, the AVI said in a media statement.

"We would welcome regulated sales of ENDS in India," Samrat Chowdhery AVI director, said. "But a ban would deny a potentially harm-reduction tool to many who would otherwise continue to use cigarettes and find it difficult to quit."

The AVI has also cited a UK House of Commons Science and Technology Committee report that has said e-cigarettes are "substantially less harmful" - by around 95 per cent - than conventional cigarettes.

A summary of the report on the House of Commons website said: "They lack the tar and carbon monoxide of conventional cigarettes - the most dangerous components. It has also proven challenging to measure the risks from second-hand e-cigarette vapour because it is negligible and substantially less than of conventional cigarettes."

But the US Centers for Disease Control has cautioned that because e-cigarettes are less harmful than conventional cigarette, it doesn't mean e-cigarettes are safe.

"E-cigarette aerosol generally contains fewer toxic chemicals than the deadly mix of 7,000 chemicals in smoke from regular cigarettes," the CDC document on e-cigarettes said. "However, e-cigarette aerosol is not harmless. It can contain harmful and potentially harmful substances, including nicotine, heavy metals like lead, volatile organic compounds and cancer-causing agents."

A WHO review on e-cigarettes had in December 2015 observed that "even though no firm conclusions can be drawn on the safety of e-cigarettes, there is an increasing body of evidence indicating harm".