Thailand is cracking down on cannabis users, prompting a new warning for Australian travellers.

Health Minister Somsak Thepsutin signed an order earlier this week that bans shops from selling cannabis to customers without a prescription.

It also seeks to reclassify cannabis buds as a controlled herb.

The order did not detail any punishment for the violation.

It will take effect when it is published in the Royal Gazette, although it was unclear when that would happen.

In the meantime, Smartraveller updated its warning for Australians looking to visit the popular holiday hotspot.

"The use of cannabis is limited to medicinal purposes only," the current warning notice reads.

"The content of Tetrahydrocannabinol (THC) must be below 0.2 per cent in weight and you must have a prescription."

Overall, Smartraveller urges visitors to exercise a "high degree of caution", also citing the risks of terror attacks, political unrest, and drink spiking.

Thailand previously became the first Asian country to decriminalise cannabis in 2022.

The ruling Pheu Thai Party previously promised to criminalise the drug again, but faced strong resistance from its former partner in the coalition government, the Bhumjaithai Party, which supported the decriminalisation.

Bhumjaithai quit the coalition last week over a leaked phone call between Prime Minister Paetongtarn Shinawatra and former Cambodian leader Hun Sen.

Somsak told reporters on Tuesday that he would like to relist cannabis as a narcotic in the future.

The move came after officials last month revealed that cannabis smuggling cases involving tourists had soared in recent months.

- Reported with Associated Press.

DOWNLOAD THE 9NEWS APP: Stay across all the latest in breaking news, sport, politics and the weather via our news app and get notifications sent straight to your smartphone. Available on the Apple App Store and Google Play.