They quoted Mua A Lau, 29, and Khang A Sinh, 32, as saying they had bought the drugs from a Laotian man and transported them from Son La Province when they were captured in Vinh Trai Ward in Lang Son City on Tuesday.

They are investigating further.

Vietnam is a key trafficking hub for drugs from the Golden Triangle, an intersection of Laos, Thailand and Myanmar and the world's second largest drug producing area after the Golden Crescent in South Asia.

Though it has some of the world's toughest drug laws, including death for smuggling and trading, drug operations continue to be busted almost every week.