The men were on their way to deliver the illicit drugs to customers in Ayutthaya.
Pol Maj-General Surapol Tuanthong, chief of the Office of the Narcotics Control Board, told a press conference yesterday the arrests were the result of previous police investigations, and a crackdown on the illegal drug ring, allegedly led by Myanmar-based druglord Lt-Colonel Yi Sae.
The suspects reportedly confessed to receiving the ‘yaba’ pills from a supplier in Mae Chan district.
The 500,000 pills were allegedly part of a batch of 6-million produced by the druglord. Police had previously seized 400,000 pills in a separate incident, in Ayutthaya.