La Van Toi, the centre's director, told the media on December 22 that the two male wallabies died on December 8 and 12.
"They both developed breathing difficulties before dying, which might have been caused by the cold weather," Toi said. "Two others including a male and a female are still in good health."
The official added that they've contacted a firm to import grass from Australia which is the wallabies' favourite food but the products haven't arrived yet.
The four animals were brought to the centre in late November after being spotted hopping along a roadside in the neighbouring Cao Bang Province earlier the same month.
They are living in a 200-square-metre semi-wild area. The caged area also has a heater which helps keep them warm in the cold winter weather.
Toi said that the animals have three meals a day, consisting of 70 percent hay, and 30 percent fresh vegetables and fruits.
Experts said that the four wallabies, which weigh between eight and nine kilos, might have been brought from Australia by traffickers who were transporting them to China.
