Police in the central province of Ha Tinh impounded a passenger bus on Tuesday night after discovering a dozen rare monkey carcases in its luggage compartment.
Investigators identified the animals as François’ langurs, a species that has been severely threatened by poaching.
Traffic officers stopped the bus at around 10 p.m. and discovered the carcases wrapped in paper and packed in a suitcase.
The wild animals had been disemboweled and dried.
Provincial forest rangers and environmental police have taken over the case.
Adherents of Chinese medicine believe that wine made out of the protected primate's bones can cure fatigue and rheumatism.
Deforestation has also contributed to the steady decline of the population over the past 30 years. Fewer than 500 wild individuals are believed to remain in Vietnam, and around 1,500 in China.
The International Union for Conservation of Nature has listed the species as endangered while Vietnam strictly bans commercial exploitation of the species.
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