LOS ANGELES, April 1, 2008 (AFP) - A tattered parachute found in a rugged region of northwest Washington state did not belong to the robber behind a daring high-altitude hijacking 37 years ago, a report said Tuesday.

The local Columbian newspaper quoted an expert as saying that the recently unearthed chute was made of different material to the one used by hijacker D.B. Cooper, who leapt from a jet in 1971 after collecting 200,000 dollars ransom.

'The D.B. Cooper parachute was made of nylon,' expert Earl Cossey told the paper. 'This 1945 parachute was made of silk.'

The discovery of the parachute last month raised hopes that it may shed light on the fate of Cooper, who was never seen again after leaping from an exit of his jet following his daredevil hijack.

FBI investigators have for years said Cooper most likely did not survive the jump from 10,000 feet, but the hijacker's body has never been found.

The case is often described as the world's only unsolved hijacking, and began when a man travelling as Dan Cooper threatened to blow up a plane flying from Portland to Seattle.

Cooper demanded 200,000 dollars and four parachutes, which were given to him after the plane landed at Seattle airport. After the plane took off Cooper made his getaway.

None of Cooper's ransom money ever found its way into circulation although nearly 6,000 dollars was found along the banks of the Columbia River in 1980.