The navy seized 139 kilogrammes of compressed marijuana in brand-name suitcases abandoned along the Mekong River in Nong Khai late Friday night.
Nong Khai governor Suchart Noppawan on Saturday announced the seizure at the naval office in Si Chiang Mai district.
The drugs, worth about one million baht, were seized by a team of naval officers dispatched to the Mekong River on Friday night following information that a drug gang planned to smuggle them into the country from Laos via the river, Thai media reported on Saturday.
The team later found eight brown brand-name suitcases left abandoned at the river bank in Kong Nang village of Tha Bo district. A sack of fish feed was also found nearby.
The officers hid in the area for more than an hour to see if anyone would pick up the bags. However, nobody showed up. They then opened the locked suitcases and found the compressed marijuana inside.
The drugs, priced at 3,000 baht a kilogramme in Laos, could fetch up to 8,000 baht a kilogramme in Thailand, said authorities.