The drugs, 33kg of them, were in plastic barrels and tea packages with Chinese writing on top, and were found by locals over a 220 km stretch of coast in Quang Tri, Thua Thien-Hue and Quang Nam provinces between November 30 and December 3.

The Ministry of Public Security is investigating the origin of the drugs.

Colonel Hoang Van Man, head of the Quang Nam Province Border Guard Department, is concerned since such a large amount of drugs had never been found in the province before.

With smuggling by land becoming difficult, drug traffickers have turned to sea routes, he reckoned.

"It must have been deliberately dropped into the water when confronted by Vietnamese forces."

A bag of heroin washed ashore and handed over to police in Quang Nam Province
on December 4, 3019. Photo by VnExpress/Dac Thanh.

Colonel Nguyen Van Hien, his Thua Thien-Hue counterpart, thought the cargo possibly fell into the sea when traffickers' boats were struck by a storm.

"It is possible more packages are floating out at sea. If anyone notices anything suspicious, we would like to be informed immediately."

His hypothesis is supported by the discovery of life-saving appliances with Chinese writing washed ashore in Thua Thien-Hue on December 4.

A box carrying Chinese words of some food inspection dates is washed ashore
in Thua Thien-Hue Province, December 4, 2019. Photo by VnExpress/Ngoc Binh.

Major General Pham Van Cac, head of the Investigation Police Department on Drug-related Crimes at the public security ministry, said there could be a connection between the drugs washed ashore and a trafficking ring busted in Ho Chi Minh City early this year.

He was referring to the seizure of 300 kilograms of meth on their way to Taiwan in March, the largest drug haul in the city's history.