A critically endangered species of rhinoceros has been poached to extinction in Vietnam, wildlife groups said Tuesday after determining that a Javan rhino found dead last year was the last of its kind.

The WWF and the International Rhino Foundation (IRF) pronounced the Javan rhinoceros extinct in Vietnam after all dung samples in a 2009 and 2010 survey at Cat Tien National Park were confirmed to have been from the same animal.

The park was the only known habitat in Vietnam for the Javan rhino, which is slightly smaller than its counterparts living in Africa, India and Nepal and described by the WWF as "probably the rarest large mammal on the planet".

"The last Javan rhino in Vietnam has gone," said Tran Thi Minh Hien, WWF Vietnam country director. "Vietnam has lost part of its natural heritage."

WWF said poaching was the likely cause of death for the rhino, which was found in April 2010 with a gunshot wound to its leg and its horn hacked off in Cat Tien, around 160 kilometres (100 miles) from Ho Chi Minh City in the south.

The group said "ineffective protection by the park was ultimately the cause of the extinction" and warned that illegal hunting to supply the wildlife trade threatened the futures of other rare animals in the country.

"The tragedy of the Vietnamese Javan rhinoceros is a sad symbol of this extinction crisis," said Nick Cox of WWF's species programme in the Greater Mekong.

Rhinos are one of the most sought after species for traditional medicine in Asia, with the horn fetching as much as $100,000 per kilogramme ($45,000 per pound), according to WWF. Many in Vietnam believe horn can cure cancer.

At a press conference in Hanoi, Cox said it was "incredible" that people would pay such large sums for the horns, when they are made from the same substance as human fingernails and have "no medicinal value".

Tran Van Thanh, of the Ministry of Health's department of traditional medicine said most practitioners did not believe that rhino horn was an effective remedy, but added that "rich people can get anything" making the trade "difficult to stop".

The rhinoceros was believed to be extinct on mainland Asia until 1988 when one of the animals was hunted from the Cat Tien area, leading to the discovery of a small population.

Javan rhinos are critically endangered, with barely 50 individuals left in a single group in a small national park in Indonesia.

WWF said Asia's voracious demand for rhino horn continues to increase every year, meaning "protection and expansion of the Indonesian population is the highest priority".

Vietnam held talks with South Africa last month as the African nation battles soaring rhino poaching. South Africa saw 333 rhinos killed for their horns last year and has already lost over 300 in 2011, compared with just 13 in 2007.

Other species on the verge of extinction in Vietnam include the tiger, Asian elephant and Siamese crocodile, WWF said.