The Intellectual Property Department had received and accepted a foreign firm's application for a patent on cannabis extract, but would not approve it, director-general Thosapone Dansuputra said on Monday
The application could not be rejected out of hand because it was submitted with all the required documentation.
That did not mean the application would be approved, he said.
Thai law barred issuing a patent for a natural extract from a plant, and this would apply to a cannabis extract.
He was responding to concerns expressed by the Government Pharmaceutical Organisation, which has invested 120 million baht in a new factory to develop cannabis products for use in medical treatment.
Media quoted GPO chairman Sopon Mekthon as saying the Intellectual Property Department had announced the foreign patent application on its website, and concerned parties had 90 days to file objections. The period had passed without any objection because no concerned parties had been aware of it, he said.
Dr Teerawat Hemachuta, of Chulalongkorn Hospital, was quoted as saying that acceptance of the application automatically prohibited any other parties from developing cannabis products, even though it had not been approved.
He asked why the department had not rejected the application in the first place.