Liberal and Labor have agreed to ban the sale of electronic cigarettes to children under 18, if either wins government in the NSW election.

Heart Foundation NSW wants a ban on the sale of e-cigarettes to children and on their use in enclosed spaces and outdoor public areas. It has called on election candidates to publicly back a law change, as part of a five-point election commitment.

Liberal Member for Kiama Gareth Ward met the foundation's Illawarra/Shoalhaven regional health promotion co-ordinator Andy Mark last year to discuss e-cigarettes.

"They [the foundation] raised their concern about the loophole that exists in the current legislation that allows these devices, and liquid nicotine, to be sold to minors," Mr Ward said.

"That is an absolute disgrace that must be resolved. I wrote to the Health Minister [Jillian Skinner] literally that day and demanded that it close that loophole and very quickly the government and the minister have assured me that legislation would be introduced."

Mrs Skinner said that if the Baird government was re-elected it would introduce a bill in the first session of Parliament to make it an offence to sell e-cigarettes and related products, including liquid nicotine, to anyone under 18.

"The sale and possession of liquid nicotine is already illegal under NSW poisons legislation," she said.

But Labor plans to go further, releasing a policy which Keira MP Ryan Park said would be the most comprehensive controls on e-cigarettes in Australia.

"If elected, that would be a ban on sale to minors ... but we will also place restrictions on the use of e-cigarettes and vaping, similar to the current laws that apply to tobacco.

"We'll also place restrictions on advertising and promotions at retail outlets and hold a public inquiry into e-cigarettes and vaping."

Mr Mark said e-cigarettes were used to prevent people from quitting tobacco.