LOS ANGELES, Oct 2, 2008 (AFP) - Rescuers in California believe they may have found the wreckage of the small plane piloted by adventurer Steve Fossett when he disappeared more than a year ago, officials said Thursday.

The National Transportation Safety Board said in a statement that wreckage of what looked like Fossett's single-engine aircraft had been spotted in the rugged terrain of the Sierra Nevada Mountains.

Search and rescue teams began combing the area near Mammoth Lakes on Wednesday after the discovery of aviation identity cards bearing Fossett's name, a faded fleece sweatshirt and 1,005 dollars cash.

Hiker Preston Morrow told US media he had not recognized Fossett's name when he discovered the identity cards and cash earlier this week.

'I came across the I.D. Card and the other card and the 100 dollar bills in the dirt and the pine needles and stuff and I went, wow,' Morrow said.

'There wasn't a picture of Fossett, but there was a name and I.D. And stuff ... It didn't pop in my head right at that time who that was.'

The location of the items was well within the range of the private airfield in Nevada that Fossett took off from on a solo flight on September 3, 2007 before he vanished.

Fossett's disappearance baffled rescuers who found no trace of the 63-year-old adventurer despite a massive search that involved dozens of aircraft taking to the skies to scour the region.

A multi-millionaire who made his fortune dealing stocks in Chicago, Fossett set dozens of world records in sailboats, gliders and hot-air balloons.

He famously made the first solo nonstop, non-refueled circumnavigation of the world in 67 hours in the Virgin Atlantic GlobalFlyer. In 2002, he was the first person to fly solo around the world in a balloon.

In February, an Illinois judge declared Fossett legally dead at the request of his widow, who issued a recent statement that there were 'no further plans for additional searching.'

Fossett's iconic status and the unusual circumstances around his demise have brought comparisons to the enduring question of what happened to aviator Amelia Earhart, who vanished over the Pacific Ocean in 1937.

Fossett's friend and fellow adventurer, British tycoon Sir Richard Branson, said he believed the items found this week were genuine and hoped the discoveries would lay to rest conspiracy theories surrounding the case.

'The positive thing is that today, a couple of stories that have appeared in the press, they'll be put to rest once and for all, and everybody who was close to Steve will have the chance now to pay the right a tribute to what was a truly great and extraordinary person,' Branson told Sky News television.

'They're definitely authentic belongings, it was his pilot license, his drivers license, it was also a membership card to the national aeronautic association which gave Stephen an award a couple of years ago,' Branson said.

'He also often carried 100-dollar bills with him so we are certain that these are genuine findings.'