Eight companies linked to the sale of synthetic cannabis are pledging to test all ingredients imported into New Zealand.
The announcement comes after the Ministry of Health banned herbal products Kronic Pineapple Express and Juicy Puff Super Strength for containing the illicit sedative phenazepam.
The companies say its new testing programme will be conducted in New Zealand and the results will be open to scrutiny.
The group also says it will stop advertising on radio, in print and outside shops.
However, it says member companies will keep their websites running and will still advertise at point of sale.
The group believes it represents most suppliers of synthetic cannabis in New Zealand.
Minister not impressed
Associate Health Minister Peter Dunne says he is deeply cynical of the voluntary code of practice announced ahead of tough new rules on the sale of drugs.
Mr Dunne says the industry has done nothing to keep its customers safe and is only self-regulating now to protect its stream of income.
The minister says changes to the Misuse of Drugs Act, to be introduced in the next few weeks, will go further than the code - and be enforceable.