Vietnamese police carrying out a routine traffic check found a pair of dead tigers in a car's boot.
The car was pulled over in Quang Binh province for breaking the speed limit. They searched the car and found the two carcasses.
The driver and a passenger were arrested and questioned. They told police that they had been hired by an unknown man to transport the bodies to nearby Quang Tri province.
The discovery throws the scale of tiger poaching and the illegal trade in body parts into further relief. In Vietnam, tiger bones are used to make medicines, including a painkiller. Despite the fact that it lacks medical backing, it is highly sought after and sells for high prices. It sells for as much as $1,000 (£620) per 100 grammes.
Poachers in parts of Vietnam and elsewhere continue to target tigers despite the the animal being pushed towards extinction.
The World Wildlife Fund has singled out Thailand as the worst country in the world for wildlife crime. It estimates that as few as 30 tigers remain in the wild in Vietnam.
The WWF said the country's decision in 2007 to legalise tiger farms on a pilot basis "undermined" attempts to police the illegal trade in tiger products. The farms have been accused by conservationists of being fronts for the animal parts black market.