The Forest Owners Association is calling on the Customs Service to adopt a zero tolerance policy on cannabis seed imports.
It is concerned at reports the service is not prosecuting all the offenders it identifies, but concentrating on repeat offenders, or those importing large quantities of cannabis seeds.
The association says it agrees with the former forestry and biosecurity minister, Jim Anderton, that the Customs Service should not be choosing who to prosecute.
Forest Owners Association policy analyst Glen Mackie says the biosecurity and public health risks are too high to allow any tolerance.
He says plant and animal diseases, insect pests and weed seeds can easily hitch-hike in the mail, while cannabis use is a major hazard, especially in safety-sensitive workplaces such as forestry.