Calls to ban electronic cigarettes in smoke-free areas of New South Wales, as has already been done in five other states, have now been backed by the State's Health Minister who is siding with the country's top health organisations.

Several groups like the Cancer Council, Council on Smoking Health, and Heart Foundation urged the NSW Government to legislate the change.

Queensland, Victoria, Tasmania, South Australia and the Australian Capital Territory have all enacted the ban to date.

"We don't actually know what's in the e-cigarette vapour, you could be sitting on a bus and the person sitting next to you using an e-cigarette could actually have nicotine in it and you're breathing in that vapour," said Wendy Oakes from the Heart Foundation.

"Also, if people are using e-cigarettes on buses, in offices, in trains, in cafes, in restaurants, that's going to be really difficult for those people who have quit smoking to actually maintain that.

"They'll constantly be exposed to the sight of people who are doing something that looks to all intensive purposes like smoking."

The NSW Health Minister Brad Hazzard said he supported the calls.

"I am very sympathetic as Health Minister to the calls of the various organisations who after all are just raising their concerns about a health issue that e-cigarettes could cause," he said.

"It'll be worked through on an evidence basis."

But Mr Hazzard called for a national approach on the issue.

"We all thought e-cigarettes were a happy medium but now... research is unfolding that they're problematic," he said.

"It would be preferable if we could have all Governments around the country look at this issue and try and come to an approach where it's exactly the same on one side of the border to the other."

Ms Oakes conceded that the safety of e-cigarettes is still being studied but it is alarming that young people are taking the devices up more than anyone else in NSW.

"Having this ubiquitous smoking around people then re-normalises it for children and adolescents," she said.