Thai authorities Sunday seized some 980,000 illegal methamphetamine pills worth almost six million dollars stashed in a truck thought to be heading to the capital Bangkok from northern Thailand, police said.
Acting on a tip-off, narcotics police and local military officials set up roadblocks in Chiang Rai province in the Golden Triangle region of northern Thailand. They found packs of the drug, known as "yaba", hidden in the roof of a pick-up truck.
"It is quite a big haul -- another big haul -- almost a million tablets," said deputy provincial police chief Virat Sumanaphan, estimating the value of the drugs in the capital would be up to 200 baht ($6) per pill.
Three men and a woman, all from neighbouring Chiang Mai province, were arrested on suspicion of drug smuggling.
The frontier Golden Triangle region, where the remote edges of Thailand, Myanmar and Laos meet, has long been a drug trafficking hub, with surging methamphetamine smuggling now adding to the traditional illicit opium trade.
It is estimated that at least 1.4 billion yaba tablets -- with an estimated street value of $8.5 billion -- are being produced each year in the region, according to the United Nations Office on Drugs and Crime.
The drug is mostly made in isolated mobile laboratories hidden in the forests of Shan state in Myanmar, which is also still the second-largest global source of opium after Afghanistan.