A self-taught Vietnamese mechanic was awarded by the King last month for souping-up Soviet-era armoured personnel carriers used by the military’s notorious Brigade 70, enabling them to shoot approaching targets once too low for the vehicles guns to address, according to Vietnamese media reports.

Vietnamese national Tran Quoc Hai, who runs an agricultural machinery factory, was reportedly in the Kingdom to provide technical support to buyers of his cassava farming machinery when he saw the unit’s sorry-looking vehicles.

Using $25,000 from his own pocket, Hai retrofitted the armoured cars, reducing their fuel consumption and strengthening their firepower along the way.

With assistance from his son, Tran Quoc Thanh, he was then contracted to revamp 10 more vehicles and to build one of his own.

His self-designed six-wheel contraption is equipped with heavy machine guns on both sides and can now hit targets as close as 7 metres, according to Vietnamese media.

Multiple reports say the pair were awarded by King Norodom Sihamoni for their work.

Previously, Hai designed a homemade helicopter, which officials in Vietnam politely declined a test flight. Firmly grounded, in 2010, it was used in an installation at New York’s Museum of Modern Art.

Officials at Cambodia’s Defence Ministry could not be reached to confirm the reports. But while the father-son team’s achievements have reportedly been celebrated by the palace, rights activists were less enthused.

“Sadly, it looks like Brigade 70 gets whatever it wants whenever it wants, and those who assist them are also heavily praised,” said Phil Robertson, deputy director of Human Rights Watch’s Asia division.

“This unit has been one of the worst rights-abusing military units all along, and giving them more capacity and capability raises some very disturbing questions about what sort of game is afoot here,” Robertson continued.

Ou Virak, chairman of the Cambodian Center for Human Rights, said he wasn’t concerned about the tanks being used on demonstrators.

“They can give them AK-47s and they still kill enough people,” he said.