A "substantial" population of 455 critically endangered northern white-cheeked crested gibbons were found living at high altitudes and far from human settlements on the border with Laos, Conservation International (CI) said.

Researchers, who had previously found sparse groups in other areas, used the animals' "loud, elaborate and prolonged" calls to locate the creatures in Pu Mat National Park in Nghe An province, northern Vietnam.

The community represents two thirds of the total number in Vietnam and the "only confirmed viable population" of the variety in the world.

"This is an extraordinarily significant find, and underscores the immense importance of protected areas providing the last refuge for the region’s decimated wildlife," said CI president Dr Russell Mittermeier.

Gibbons, which are threatened across the world, are considered the "most romantic" of primates as they mate for life and serenade their partners with songs.

Habitat loss, hunting for the pet trade, and the "assumed medicinal value of primate body parts" are among the major threats to the creatures in Vietnam, the CI statement said.

AFP