False alarm in Fossett search

Rescuers are still combing rugged country for signs of the light plane of Mr Fossett. (Reuters: Rick Fowler )

Concerns are growing for millionaire adventurer Steve Fossett who has been missing in the United States since early on Tuesday.

Rescuers in Nevada are still combing 1,500 square kilometres of rugged country for signs of his light plane.

Hopes were raised when searchers spotted a plane wreck earlier today, but Major Cynthia Ryan from Nevada's Civil Air Patrol says it was not the aircraft of Mr Fossett.

"We thought we had it nailed. Unfortunately it turned out to be one of many dozens unmapped wreck sites from previous years," she said.

"We found that out by sending in a helicopter and they put a man on the ground and verified that it was not the target that we were looking for, it was not Mr Fossett or his aircraft."