Synthetic cannabis has become so popular that a specialist store has opened in central Auckland.

The Highllusion shop in Hobson St has a cannabis leaf on its signs, and a glass cabinet inside displays several brands of "legal weed".

Owner Bunleng Chhun, who also has the neighbouring Hobson Liquor Store, could not be reached yesterday.

However, a shop assistant said staff always asked for identification.

The assistant pointed out that the store displayed an Expert Advisory Committee on Drugs report on synthetic cannabis such as Kronic.

That report noted the case of a 20-year-old who suffered nausea and tremor after detoxing from heavy use of synthetic cannabis.

Synthetic products such as Kronic are widely available in dairies and contain chemicals that closely mimic the effects of cannabis.

Police have said buying Kronic is as "easy as buying chewing gum" for those aged under 18.

Highllusion also sells pipes, party pills and tobacco, although much of its display space is taken up by varieties of synthetic cannabis.

Chris Fowlie, the co-owner of the Hemp Store, which has sold synthetic cannabis products for 10 years, said he was concerned about the substances' availability.

"It's gone too far, especially with its availability in dairies ... Dairies are often by schools, and they often put posters covering their front walls," he said.

"I think a lot of parents out there can tolerate these sorts of products if they're not in mainstream shops. You go in there for your bread and milk and you're confronted by what are drugs.

"It's crossed over so that people who don't even smoke cannabis are trying this stuff. And that's where it goes too far."

Mr Fowlie said a licence should be necessary to sell the R18 products.

Products such as Kronic were not advertised at the Hemp Store, and Mr Fowlie said that was important.

"It shouldn't be plastered all over the front of the shop. If you're not interested in these products you really shouldn't know about them."

A legislative amendment expected to be passed next year will clamp down on where the products can be sold and greatly restrict how they can be advertised.

The forensic general manager at the Institute of Environmental Science and Research, Keith Bedford, told the Herald last week that such products appeared to be low risk - however he noted an "appalling" lack of data on the substances.

Western Australia's Health Minister, Kim Hames, announced on Monday that the state Government would ban synthetic cannabinoids such as Kronic.

The state branch of the Australian Medical Association had been calling for Kronic to be outlawed, saying it had dangerous side-effects.