The New Zealand Drug Foundation said the medical cannabis industry in New Zealand will face competition from overseas medical cannabis companies.
But three United Nations drugs treaties prevented the global trade in non-medical cannabis - that which might be used recreationally - should New Zealand laws change on the use of recreational cannabis.
A Thai drug company has told RNZ its low-priced imports may eventually undercut New Zealand's cannabis market, and investors were not being properly warned.
Drug Foundation executive director Ross Bell said it was important for people to understand that products used in medicinal cannabis could be imported and exported, meaning New Zealand producers could join the global industry, and equally they could face competition from overseas medical cannabis companies.
"But when it comes to recreational cannabis, including if we legalise it with the referendum, there are three United Nations drugs treaties which don't allow the global trade in non-medical cannabis."
The Ministry of Health said medicinal cannabis products, except for CBD products, were controlled drugs under the Misuse of Drugs Act 1975. Medicinal cannabis licence holders also required a controlled drug import or export licence if they intend to: Import cannabis seed, starting material, a cannabis-based ingredient or a medicinal cannabis product, and export cannabis starting material, a cannabis-based ingredient or a medicinal cannabis product.
New Zealand's Business and Economic Research agency Berl told RNZ it understood that "there was no intention (or allowance) for the importation of product except for cannabis plant seeds".
The vice president of marketing of the Thai Cannabis Corporation has queried statements by Berl that "low-priced products would be excluded".
Jim Plamondon said it "flatly contradicted the New Zealand-Thai Closer Economic Partnership, which was the prevailing law for such trade in medical cannabis.
"New Zealand cannot exclude Thailand's exports of medical cannabis on the basis of its low price, or deny it the market share that that low price would naturally attract, through quotas, tariffs, or non-tariff trade barriers," he said.
Bell said commercial interests were pushing their own interests, and confusion was apparent because of the stage the industry was at, but the prospects for the New Zealand medical cannabis industry were exciting.
"There are a few players getting licences and who are crowd-funding, and investors are getting quite excited about the prospects.
"The New Zealand medical cannabis industry will be competing with the global industry and there are some massive companies in North America - particularly Canada, that can compete with New Zealand."
Bell said there were also burgeoning markets, like Thailand which might be able to produce medical cannabis much more cheaply, but it would still need to meet New Zealand's strict pharmaceutical standards.