BANGKOK • Ten million made-in-Myanmar "yaba" pills and nearly half a tonne of crystal meth hidden in tea packages have been pulled from a convoy of cars in Bangkok, Thai police said.

The drugs - worth around US$45 million (S$60.1 million) on the local market - were being ferried along Thailand's "narcotics corridor", which cuts through the central Thai province of Ayutthaya to Bangkok and then south to Malaysia.

Police followed the four cars from Ayutthaya, which is a key warehousing site for drugs pouring from Myanmar's meth labs.

They made the bust once the convoy reached downtown Bangkok late on Thursday, police said yesterday, uncovering crystal meth concealed in Chinese-branded tea packages and the pill bundles.

"Six Thai suspects who were paid to transport drugs were arrested," national police chief Chaktip Chaijinda told reporters, adding some of the drugs were "destined for foreign countries".

"They belong to the northern Wa group," he said, of an ethnic group based in Myanmar's Shan State which jointly oversees the world's second largest drug producing region.

Yaba - which means "crazy medicine" in Thai - tablets are methamphetamine pills cut with caffeine and are consumed across Asia. The notorious "Golden Triangle" - an ungovernable border zone that crosses Myanmar, Laos, Thailand and China - is experiencing a boom in drug production.

Massive oversupply from Myanmar has seen the price of a yaba tablet plummet to 100 baht (S$4.20) in Thailand.

The much more potent and addictive crystal meth version - "ice" - is also cascading across the region.

One kilo goes for around US$30,000 in Thailand, but the price rises the further it is transported from the source in Myanmar. Drugs are trafficked south to Malaysia and beyond, while record seizures are also being made along a westwards route from Myanmar to Bangladesh.

Rohingya refugees are moving them across Bangladesh's Cox's Bazar district, which hosts around one million of their stateless Muslim minority.

And drug money is bringing new problems to an already traumatised refugee community. The Bangladesh authorities warn that shootings, extortion and kidnappings linked to drug disputes are on the rise, adding another layer of complexity and danger to life in the seething camps.

More than 100 Rohingya have been arrested on drug charges since last August, when a crackdown by Myanmar's army expelled the Muslim minority into Bangladesh in huge numbers.

AGENCE FRANCE-PRESSE