The Royal Thai Embassy in Japan has advised Thais not to enter the country in possession of cannabis or related products.
"The Thai Embassy in Tokyo would like to warn Thai people not to bring in cannabis, hemp or products containing these plants into Japan. Violators may face punishment under Japanese law," it said in a message posted on its Facebook page on Friday.
Possession of cannabis and hemp for import and export purposes carries a jail term of up to seven years in Japan, while possession for sale carries a potential 10-year term and fine of up to ¥3 million (about 786,200 baht), according to the embassy.
It also warned people to beware of receiving illegal items for delivery in Japan.
On June 21, the Thai Embassy in Indonesia also posted a warning on its Facebook page that Thai tourists should not bring cannabis or its extracts with them.
There, the fine extends to 1 billion rupiah (about 2.3 million baht), five years to life in jail or even the death penalty.
Thailand is the first country in Southeast Asia to decriminalise possession and use of the plant, after it was delisted from the government's Category 5 narcotics list for use at levels of less than 0.2% tetrahydrocannabinol (THC), cannabis' psychoactive ingredient, following the publication of a Ministry of Public Health announcement in the Royal Gazette.
Earlier, the government issued new rules to limit access to the plant by anyone under 20 years old, signed off by Deputy Prime Minister and Public Health Minister Anutin Charnvirakul on June 16.