A group of local activists on Wednesday urged the Department of Intellectual Property to withdraw drug patent requests for cannabis extract.
"It is clear that those patent requests are against Thai law, but the department ignored the law by accepting the requests," Kannikar Kijtiwatchakul, a coordinator of FTA Watch told the Bangkok Post.
"The department's chief must immediately reject those requests in one week. If not, I will invite all patient networks affected by the case to discuss the problem at his office."
She urged affected research groups such as the Government Pharmaceutical Organisation (GPO) to take the matter to court.
The Department of Intellectual Property is looking at the matter after local activists found it had accepted requests by foreign pharmaceutical companies to patent drugs from cannabis extract.
Despite Commerce Minister Sontirat Sontijirawong on Monday insisting the patent requests will not be granted, local researchers are worried because the patent application process gave protection to request submitters by preventing other researchers from working on similar extracts.
Ms Kannikar said the department has a lawful right to reject companies applying to patent marijuana for medical use.
Section 28 in the 1979 Patent Act gives full authority for the head of the department to send a notice rejecting requests which defy Thai law.
Thai law prevents patent rights over products that come from any parts of plants and animals, and products related to medical treatment of people and animals.
Local activists have found foreign pharmaceutical companies had filed 12 patent requests with the department.
Most requests were filed by US-based GW Pharmaceuticals and Otsuka Pharmaceutical company from Japan.
They are involved with treatment of cancer and epilepsy.
Among affected local research groups is the GPO, that invested 120 million baht for a cannabis plantation trial in Pathum Thani.
GPO's board chairman Sophon Mekthon said previously that the chief of Department of Intellectual Property had informed him the department was not able to grant a patent for cannabis product as it is against the law.
However, the board will evaluate risks that may occur to the organisation.
Dr Sophon did not say whether the GPO will file a complaint to the department.
The cabinet on Wednesday approved a draft amendment to the 1979 Narcotics Act to legalise cannabis for medical and research purposes.