The government could be in breach of its international treaties if it banned the sale of duty free cigarettes, Prime Minister John Key says.
Health and church groups have banded together to push for a ban, and they also want much bigger tobacco tax increases than the government has so far imposed.
"It's a possibility but I'll need to get advice on whether we're legally able to do it," Mr Key said.
"My advice is we have treaties and obligations, we can't just change the law."
Global Public Health, the Royal Australasian College of Physicians, the Cardiac Society of Australia and New Zealand, the Methodist Church and others are calling for the ban and a 40 per cent hike in tobacco excise followed by three successive 20 per cent increases.
Mr Key is indicating that isn't likely.
"We've given a clear signal by increasing the price by 10 per cent a year," he said.
"What we're trying to stop is the gateway into smoking and price is the most effective deterrent to young people - there's a balance between sending that signal and being really tough on existing smokers."