A view of the Mekong river bordering Thailand and Laos is seen from the Thai side in Nong Khai, Thailand, October 29, 2019. (Photo: REUTERS)

More than 55 million amphetamine tablets and over 1.5 tonnes of crystal methamphetamine were intercepted by Laos police on Wednesday, who stopped a truck carrying beer crates in northern Bokeo, which borders Thailand and Myanmar, the two sources told Reuters.

Jeremy Douglas, Southeast Asia regional representative for the United Nations Office on Drugs and Crime (UNODC) said the discovery was "by far the largest seizure in the history of East and Southeast Asia."

The Golden Triangle - an area of northeast Myanmar that meets parts of Thailand and Laos - has a long history of being a major drug-producing area.