A New South Wales Greens MP has lit up an e-cigarette in State Parliament to prove a point about legal loopholes around the vapour devices.

Greens health spokesman Jeremy Buckingham caused a stir when he leaned back in his seat and started blowing puffs of vapour from the device during Upper House Question Time.

Government Whip Peter Phelps jumped to his feet to alert the Upper House President to Mr Buckingham's behaviour.

"Mr Jeremy Buckingham is clearly smoking a vape cigarette in this house, more importantly, he's done it with clear pre-meditation," Dr Phelps said.

"It is an outrageous act against the decorum of this house."

Mr Buckingham replied: "I'm not smoking."

The President of the Upper House, Don Harwin, reprimanded Mr Buckingham for using props, but he was allowed to remain in the chamber.

Other MPs called out that it was a "stunt" and called Mr Buckingham a "media tart".

The Government has introduced a bill to Parliament to ban the sale of e-cigarettes to minors, but the Greens and Labor say it does not go far enough.

Mr Buckingham said e-cigarettes should be dealt with under all the same laws covering tobacco and nicotine, including banning their use in non-smoking areas under the Smoke-Free Environment Act.

He said his actions in the house highlighted the double standard applied to e-cigarettes.

"I was trying to make a very important point today that under NSW law and the modest reforms of the Government, it is still legal in this state to vape in a preschool, on a bus, in a public space and even in the Parliament," he said.

"I was making the point that this is a really serious health issue and the current reforms don't go far enough in protecting the community."