Hanoi  - A species of giant turtle once thought extinct in the wild has turned up in a lake in northern Vietnam, staffers at a Vietnamese conservation organization said Thursday.

Nguyen Xuan Thuan, a field biologist and coordinator of the Cleveland Metroparks Zoo's Asian Turtle Program, said he had photographed a specimen of what he believed to be Rafetus swinhoei, commonly known as the Shanghai soft-shelled turtle, at a lake some distance west of Hanoi in June 2007.

On Wednesday, the Cleveland Zoo's renowned turtle expert Peter Pritchard confirmed the identification.

Thuan declined to reveal the location of the lake where the turtle was found for security reasons.

"If I tell you someone else will know, and they'll just come to catch and kill it," Thuan said. "The big soft-shelled turtle has a high value, so a lot of wildlife traders would like to buy it and sell it."

Turtles are highly sought after in Vietnam for their meat, which is considered a delicacy, and their shells and bones, which are used in traditional medicine.

The Shanghai soft-shelled turtle was once widespread in Vietnam and southern China, but had not been seen in the wild for years. Two are in captivity in zoos in China.

Complicating the identification of the turtle in Vietnam, at least one giant soft-shelled turtle closely resembling Rafetus swinhoei is known to live in Hoan Kiem Lake in the center of downtown Hanoi.

Professor Ha Dinh Duc, a biologist at Hanoi University, has contended for years that the turtle in Lake Hoan Kiem is a separate species, which he has named Rafetus Leloii after Le Loi, the 15th-century Vietnamese emperor who according to myth was given a golden sword by a magical tortoise at the lake.

Duc said he had not seen Thuan's photos of the turtle west of Hanoi, and could not make a judgment about whether it was of the same species as the one in Lake Hoan Kiem. (dpa)