Police in central Vietnam seized nearly a tonne of methamphetamine found abandoned by the side of the road on Wednesday, an officer told AFP, just days after another massive drug bust in the same region.
Local residents came across dozens of bags of white powder that had been left on the road near a salt field in central Nghe An province and reported them to police, an officer told AFP.
The residents thought they might be filled with salt or rubbish, but police later confirmed the sacks contained 900kg of meth, the largest recorded bust in years.
"We have identified five people related to the drugs and arrested three," the police source said, requesting anonymity.
"We are searching for the other two, who are on the run, including a foreigner," he added.
He said authorities are investigating where the drugs came from, while state media said the meth haul was destined to be shipped outside Vietnam.
The bust comes just days after police in the same province found 600kg of meth stuffed into stereo boxes in a home occupied by an elderly couple.
Synthetic drug use is on the rise in Vietnam and police have busted several homegrown labs in recent years.
But much of the country's illegal supply floods in from the lawless "Golden Triangle" zone that straddles Laos, Thailand and Myanmar.
Though older users in Vietnam have long preferred opium and heroin as their narcotic of choice, younger people are increasingly turning to party drugs such as meth, ketamine and ecstasy.
Seven people died of suspected overdoses last year at an electronic music show in Hanoi, shocking many in the conservative city and prompting the government to ban festivals.
The one-party communist state has some of the toughest drug laws in the world. Anyone caught with more than 600g of heroin or more than 2.5kg of methamphetamine can face the death penalty.