The body representing suppliers and retailers of legal highs says more needs to be done to prevent under 18-year-olds getting hold of synthetic drugs online.
The Ministry of Health has suspended shops' licences under the new Psychoactive Substances Act but the Star Trust says tighter regulation of online shops is needed.
The ministry says shops in Hawera, Dunedin and Whanganui have had their licences to sell legal highs suspended after breaking the new law.
Meanwhile, Hamilton police say two shops face prosecution after supplying synthetic cannabis to an under-age girl.
Star Trust general manager Grant Hall says although he's pleased irresponsible shop owners are being caught, there's a gap in enforcing the law online, with no guarantees all customers are over 18.
The ministry says requirements for buying synthetic drugs online are the same as for buying alcohol online.
Julie King, who organised a protest against the sale of legal highs in Tokoroa, says shop owners who break the law to sell them are just greedy and selfish.
She says they continue selling them because the money is too good for them to resist.
Hamilton police say a 35-year old man arrested in Garden Place on Sunday was found with $3000 and 65 unmarked packets of what's thought to be synthetic cannabis.
He's been charged with selling or supplying a non-approved psychoactive product.
Hamilton licencing supervisor Sergeant Jim Kernohan says two licenced stores also face prosecution after selling synthetic cannabis to a 17-year-old.