Associate Health Minister Peter Dunne says a further three synthetic cannabis substances are expected to be off the market by the end of next week.
Mr Dunne says Customs intercepted the substances at the border and temporary class drug notices are being issued to ban them.
In August this year, the Government made changes to the law banning more than 40 synthetic cannabis products, such as Kronic, for 12 months.
Mr Dunne says it is possible that a new synthetic cannabis drug for sale in Auckland under the name Amsterdam Cafe contains one of the three banned substances and has instructed health officials to investigate and test the product.
The minister says the industry has misread the scope of the law if it thinks it can get around it by changing products' ingredients and packaging.
A Massey University drug researcher believes distributors may be testing the strength of the law change.
Chris Wilkins says it is fairly easy for manufacturers to come up with different variations of a drug compound.
Dr Wilkins believes companies should have to prove legal highs are safe before the products make it to the shelves. Otherwise, distributors are lab-testing unknown compounds on young people, he says.
