Inspectors with Vietnam's Ministry of Public Security have proposed charge of cross-broder drug trafficking against 21 people involved in a ring that was busted in July.
Their investigations found that the ring, led by 42-year-old Nguyen Ba Thuy, traded up to four kilograms of drugs in less than a year before its members were arrested.
The traffickers would bring drugs from Cambodia into Ho Chi Minh City first and later take it to Hanoi, police said, adding that the ring was also smuggling drugs from China into Vietnam.
Thuy was based in Hanoi, while his wife Doan Thi Thuy Hong, also 42, mainly operated in HCMC, the police said.
Among the ring members were three students of the Tu Son Sports University in the northern province of Bac Ninh, police added.
Vietnam has some of the world's toughest drug laws. Those convicted of smuggling more than 600 grams of heroin are eligible to get the death sentence.