Police in Nam Dinh Province in northern Vietnam on Sunday arrested a man who was carrying the frozen carcasses of four tiger cubs.
The 26-year-old from the central province of Ha Tinh, said he had bought the carcasses from a Laotian at a border market for VND2 million (US$90).
He then advertised their sale on Facebook, and a person in Nam Dinh offered to pay VND8 million for them.
He was caught while delivering them to the buyer.
The police have seized the carcasses and are holding the man for questioning, suspecting him of being a member of a wildlife trafficking gang.
Vietnam is a big consumer of tiger parts and the illegal trade has become more brazen, with traffickers offering to sell on social networks.
In Vietnam, the animal is trafficked for meat, skin and claws. Tiger bones are used for making a glue that many believe also have medicinal properties.
Uncontrolled consumption has seen an astonishing decline in the population of wild tigers in the country from more than 100 in the early 2000s to less than five now, according to a World Wildlife Fund report last month.
According to the new data, the animal is under threat in Southeast Asia, due to lack of protection.
Cambodia has lost its tigers while there are only two left in Laos.