Thai police seized 600 kilos of crystal meth from a drug trafficking ring in Thailand.

Officers intercepted two trucks carrying the hard drugs through Prachuap Khiri Khan province on September 4.

Four men were arrested in the bust at a petrol station along Phetkasem Road. They were identified as Litthikiat, 28, Somsak, 30, Suriya, 32, and Suraphon, 23.

Police said the operation was carried out following intelligence about a large delivery of drugs to southern Songkhla province. The shipment, concealed in 17 fertiliser sacks, reportedly came from Chiang Rai bordering Myanmar near the Golden Triangle.

Police Lieutenant Colonel Thotsaphon Kitilarp of the Highway Police Division said: 'The suspects were charged with jointly distributing Category I narcotics for sale without permission. This action is for commercial purposes, leading to its spread among the public and impacting national security and the safety of the general public.

‘All of the suspects admitted to the charges after we informed them of their offences and rights. The arrest team took them and the seized items to the station to expand the investigation.'

Meth is classified as a category 1 substance in Thailand.

Under Thai law, using category 1 substances may be punished with up to three years in jail and a fine of up to 60,000 baht, while possession carries a fine of up to 200,000 baht and up to 10 years imprisonment.

Those convicted of dealing may face life imprisonment and a five million baht fine, depending on the amount involved. Producers, importers, and exporters of Category 1 substances face the same charges and may face the death penalty if it is proven their intent was to sell or distribute on a large scale.

Chiang Rai, where the meth was believed to have been sourced, sits along the Golden Triangle, where most of Southeast Asia's meth supply comes from.

The region is found where the borders of Thailand, Laos, and Myanmar meet but it has long been a feral nest of criminal activity, including opium production, meth labs and call centre scam bases.

At the heart of the Golden Triangle lies the Golden Triangle Special Economic Zone (GTSEZ), run by notorious Chinese business tycoon and suspected crime boss Zhao Wei in the Chinese vassal state Laos. Communist chiefs are said to turn a Nelsonian eye to his wrongdoing.

In 2007, Zhao brokered a deal with the Laos government and obtained a 99-year lease to build the zone on a 39-square mile patch of impoverished Bokeo province.

The Chinese businessman claims to be a benefactor as he touts the GTSEZ as a tourist and economic hub designed to bring more income and investments into the country. However, both local and international law enforcement agencies believe it is a front for organised crime, including human trafficking, drug trafficking, and call-centre scams.

International authorities have struggled to take down the gambling empire as the Laos government itself is said to be protecting the GTSEZ, in which it has a 20 per cent stake.