Thais stand to gain from the state push to legalise marijuana for medical purposes despite concerns the move may benefit transnational drug manufacturers.

The assurance was given on Monday by Deputy Prime Minister and Justice Minister Prajin Juntong who tried to alleviate fears, especially those related to controversial requests from foreigners to patent substances that have cannabis extracts as a component.

When the National Legislative Assembly, which is currently deliberating a marijuana bill, passes it into law in January, doubts over its use should be eased.

"So don't be worried," ACM Prajin said.

Everything will be under the control of the government which will make sure "all benefits will go to the Thai people and the country," he said.

At present, the Commerce Ministry is looking into the issue of patents, and this too will be made clearer after the law takes effect, ACM Prajin said.

There were 11 patent requests lodged with the Department of Intellectual Property and two of them have already been withdrawn, Commerce Minister Sontirat Sontijirawong said earlier in response to concerns that they will hinder attempts to utilise marijuana.

He admitted it is not an easy issue to resolve as it involves the Patent Act, which is quite complicated and involves a lengthy process, but assured local researchers are still able to use cannabis extracts to produce medicines or precursors that can be used to make them.

Other agencies are also preparing to ensure the legal use of cannabis benefits both Thai medicine developers and patients.

The Public Health and Justice ministries are drafting measures ACM Prajin said could be implemented immediately after the law is enacted.

He said officials must make clear what the whole process for utilising cannabis for medical purposes entails.

The number of patients needing marijuana will be used to determine the amount of land needed to grow the crop, ACM Prajin said. Excess amounts of cannabis should be destroyed, he said.