It also found that of 59 New Zealand websites with such products, 68 percent had no obvious health warnings, and only 25 percent mentioned nicotine addiction.
A Ministry of Health spokesperson said there were practical barriers to enforcing the smoke-free legislation for vaping products because the law only applied to nicotine manufactured from tobacco, nor did it cover devices that contained no nicotine.
Last year the ministry lost a legal fight to stop the tobacco giant Philip Morris importing and selling tobacco sticks designed to be heated instead of burned like cigarettes.
George Thomson, of Otago University, said companies were either flouting the law or thought it did not apply to them.
"It's essential that we have a effective way of age proof. We have a system which the govt uses for e-commerce and we need that sort of system where there is proof of identity to be applied for youth purchases."