Highway police arrested a man with 350kg of dried marijuana in his possession in Nam Phong district of Khon Kaen province on Sunday morning.
The seizure took place after highway police manning a checkpoint between kilometre markers 384 and 385 on the Bangkok-bound side of the Mitrapap Highway in Nam Phong district searched a Toyota Jazz car which had been parked on a roadside.
They found 350 bars of dried marijua in the rear of the car.
The driver, Suwan Simmathong, 33, of Ubon Ratchathani's Samrong district, was arrested and charged with having illicit drugs in his possession with intent to sell.
The man said he had been hired by Uthai Thiapnoo, 44, of Maha Sarakham province, for 30,000 baht to deliver the drugs from the banks of the Mekong Rover in Bung Khla district of Nakhon Phanom province to a client in Bangkok's Nimit Mai area.