A critically endangered mammal known as the 'Asian unicorn' has been sighted in the wild in Vietnam for the first time in over a decade, raising hopes for the recovery of the animal.

The saola, a twin-horned, antelope-like creature known for its elusiveness, was caught on a camera set by the WWF in a central mountainous region of Vietnam.

Conservationists believe there could be only a few dozen saola surviving in the wild, and efforts are underway to protect them from hunters.

In a statement, WWF Vietnam's country director Van Ngoc Thinh said when the team first saw the photos they "could not believe [their] eyes".

"Saola are the holy grail for South-East Asian conservationists, so there was a lot of excitement," he said.

"This is a breathtaking discovery and renews hope for the recovery of the species.

"Confirmation of the presence of the saola in this area is a testament to the dedicated and tireless efforts of these forest guards."

The last sighting of a saola in Vietnam was in 1998.

In the area where the saola was sighted, the WWF runs a law enforcement program which recruits forest guards from the local community to prevent illegal hunting.

Since 2011, the guards have removed 30,000 snares and destroyed more than 600 illegal hunters' camps.

The deputy head of Quang forest protection department, Dang Dinh Nguyen, said the latest appearance of the animal was "an historic moment" and showed that conservation efforts in the critical saola habitat were effective.

ABC/AFP