An Australian mountaineer who had been believed dead near the summit of Mount Everest has been revived and has come part way down the mountain, reports said Saturday.

Lincoln Hall, 50, is being cared for at a camp on Everest at about 20,997 feet, Australian Associated Press reported.

That is some 4,921 feet beneath the so-called "death zone," where oxygen levels are so low they cannot sustain life for long.

"He's in reasonably good condition, but he doesn't have much memory of things at this stage," climber Duncan Chessell told AAP.

Chessell, who also runs DCXP Mountain Journeys, told AAP he had been in contact with a guide on Everest, Jamie McGuinness, who had passed on the news of Hall's revival.

"Basically, he's been able to come down under his own steam, without assistance, is what Jamie reported," Chessell said from the southern Australian city of Adelaide.

Hall, an experienced climber who had been on a Russian-led expedition, made it to the summit of Everest but grew gravely ill from oxygen deprivation during his descent.

The area near the top of Everest is one of the most difficult environments on Earth, where even the strongest and most experienced climbers can become desperately ill from lack of oxygen.

Hall fell ill shortly below the summit, AAP reported. His two Sherpa guides tried to help him down, but were eventually forced to leave him in order to save themselves, and Hall was then declared dead, AAP reported.

The following morning, an American climber found him alive, prompting a rescue team to help bring Hall to safety.

Hall must now walk or be carried for more than 15 miles to reach the base of the mountain.