Vu Hong Son, Tran Thi Luong and Do Duy Khanh, all in their 40s, and Le Thi Kim Anh, 37, were found guilty of "illegally trading in narcotics."

Two women accomplices, aged 40 and 34, were sentenced to 20 and 18 years in jail for the same charge.

Son, the kingpin, was also found guilty of "illegal possession of narcotic substances" and "illegal possession of military weapons."

In June 2014 the Saigon police caught Khanh with one kilogram of heroin on the street, and through him found the other members of the gang.

They also found Son and Luong possessing a gun, two boxes of cartridges and two kilograms of heroin. Son told them he had bought the gun in Cambodia. Luong did not face weapons-related charges.

Son said he had met an unidentified drug dealer and bought the heroin.

Son told the police he and his accomplices bought a total of six kilograms of heroin from this source. He also bought 1,890 ecstasy pills and asked Luong to hold all the drugs while he found customers. But before he could, the gang was busted.

Vietnam has some of the world’s toughest drug laws. Those convicted of possessing or smuggling more than 600 grams of heroin or cocaine or more than 2.5 kg of methamphetamine face the death penalty. The production or sale of 100 grams of heroin or 300 grams of other illegal narcotics is also punishable by death.