Sir Ranulph Fiennes is now on the descent to base camp after resting
Sir Ranulph Fiennes has had to abandon his second attempt to reach the summit of Everest, due to exhaustion.
The 64-year-old had hoped to reach the 8,850m summit at 0330 BST and raise £3m for the Marie Curie cancer charity.
But he had to turn back after contending with heart problems and vertigo, a spokesman said.
Sir Ranulph, from Somerset, suffered a heart attack during his first unsuccessful attempt to scale the mountain in 2005.
The explorer, accompanied by guide Kenton Cool and medic Robert Casserley, set off from base camp on Tuesday.
They had reached the final stopping-off point in the ascent after negotiating the "death zone", but descended to base camp after resting.
His wife, Louise Fiennes, told BBC News Online Sir Ranulph was keen to return to the UK.
She said: "He just called me an hour ago and asked me to arrange to get him back to Kathmandu. He's desperate to get back to the UK."
The owner of the company organising Sir Ranulph's climb, Iswari Paudel, told BBC News he would be flown out by helicopter on Sunday morning.
Sir Ranulph has never conquered Everest and was making his second attempt on the peak despite suffering from vertigo and heart problems and currently being in remission from prostate cancer.
He was the first man to reach both the North Pole and the South Pole by land, ran seven marathons in seven continents in seven days shortly after heart surgery, and journeyed to discover a lost city in Arabia described as "the Atlantis of the Sands".