BANGKOK, May. 8 (CNA) - Thailand will re-list cannabis as a narcotic by year-end, its prime minister said on Wednesday (May 8), in a stunning U-turn just two years after becoming one of the first countries in Asia to decriminalise its recreational use.

The moves come despite the rapid growth of the domestic retail sector for marijuana, with tens of thousands of shops and businesses springing up in Thailand in the past two years in an industry projected to be worth up to US$1.2 billion by 2025.

"I want the health ministry to amend the rules and re-list cannabis as a narcotic," Prime Minister Srettha Thavisin said on social media platform X.

"The ministry should quickly issue a rule to allow its usage for health and medical purposes only."

Cannabis was decriminalised for medical use in 2018 and recreational use in 2022 under a previous government, but critics say its liberalisation was rushed through, causing huge confusion about rules and regulations.

Srettha's comments followed a meeting with agencies involved in narcotics suppression, where he vowed to take a tough stand on illicit drugs and ordered authorities to deliver results and show "clear progress" in the next 90 days.

"Drugs is a problem that destroys the future of the country, many young people are addicted. We have to work fast, to confiscate assets (of drug dealers) and expand treatment," he said.

He also asked authorities to redefine what constitutes drug possession under the law, from "small amount" to "one pill", to enable tougher enforcement by authorities.

Srettha's government had earlier said it wanted to push out a cannabis law by year-end that would ban recreational marijuana and allow its use for medical and health purposes only.

It was not immediately clear when cannabis would be re-listed as a narcotic or what processes must first take place.

Prasitchai Nunual, secretary-general of Thailand's Cannabis Future Network, said re-criminalising cannabis would be a bad move for the economy and deal a big blow to small businesses and consumers.

"Many people have been growing cannabis and opening cannabis shops. These will have to close down," he told Reuters.

"If scientific results show that cannabis is worse than alcohol and cigarettes then they can re-list it as a narcotic. If cannabis is less harmful, they should list cigarettes and alcohol as narcotics too."