Thailand is poised to start its first tests of cannabis oil on patients, a health official said Friday, as excitement swirls around a new industry that could create money-making avenues for entrepreneurs while offering relief for suffering patients.

Marijuana has been used as a traditional herb for centuries in Thailand but was banned decades ago.

The junta's rubber-stamp parliament voted in December to legalize it for medical purposes.

Thailand is the first in Southeast Asia to embrace medical marijuana though recreational use remains illegal.

Now state-sanctioned clinical trials testing the impact of cannabis oil on selected patients will be held as early as July, according to Nuntakan Suwanpidokkul, director of research and development at the Government Pharmaceutical Organisation (GPO).

Extracts or "sublingual drops" will be administered during the tests to volunteers suffering from nausea and pain from chemotherapy, among other ailments.

"We will use cannabis plants to extract oil for finished products," Nuntakan told AFP, adding that "we hope to begin in July or August".

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They will come from the government-managed indoor plantation that opened last month on the outskirts of Bangkok.

It has around 140 plants cultivated under controlled lighting, temperatures and a misting system known as aeroponics.

A gold rush mentality has set in since Thailand's parliament voted to change to the law.

Political parties are touting the cash crop's benefits for the livelihoods of farmers and big blowout festivals are planned for April.

The country's Food and Drug Administration also announced a 90-day amnesty starting in March for Thais to declare marijuana used for medical reasons and it has received thousands of calls asking for more details.

Several nations have legalized medicinal cannabis, including Canada, Australia, Israel, and more than half the states in the US.

US-based Grand View Research has estimated the global market for medical marijuana could reach $55.8 billion by 2025.

But critics caution that Thailand lacks the technical know-how to be truly competitive in the lucrative industry.

"What I feel that the law is lacking is that the people who are writing it don't understand that cannabis is a very finicky plant," said Kitty Chopaka from the Highland Network, which advocates for marijuana legalization.