Sir Ranulph's desert trek 'hell'
Sir Ranulph Fiennes has been taken to the medical tent at the Marathon des Sables following concerns for his health.
The 71-year-old explorer is receiving medical attention after running for 30 hours in over 50C (122F) heat.
Sir Ranulph completed the most gruelling stage of the Marathon des Sables earlier today, but was taken straight to the medical tent as the exertion had begun to take its toll on his heart.
The veteran explorer, who has previously suffered two heart attacks and underwent a double heart bypass in 2003, was forced to lie down intermittently during the last few hours of the race, after fears he would not be able to finish the stage.
Speaking from the medical tent, Sir Ranulph said the last few hours had been "more hellish than hell".
He said: "I became woozy and had the feeling I was going to faint. It's not worth pushing it when you get that.
"My trainer Rory had to push me down to the ground to rest and then pick me up again every so often, that is how we made the last 5k.
"Last night was pretty horrific, it's hell on earth. You're trying to go up hills and your feet are slipping backwards in the sand. I had some really shaky moments. My head-torch faded and I couldn't see the hills."
But Sir Ranulph, who is pushing to become the oldest Briton to complete the six-day ultra-marathon in the South Moroccan desert, said thoughts of the Marie Curie teams he is raising money for kept him going.
He said: "What kept me going was the thought that Marie Curie nurses are also working through the night.
"This is all to raise funds for the amazing care they provide to people who are terminally ill and their families."
Sir Ranulph, who began the challenging fourth stage of the event at 8:30am on Wednesday, has covered 56 miles, stopping for an hour at 04:30am this morning to sleep out on the race course.
But the race, which has already seen more than 75 people drop out, is still not over and Sir Ranulph still has one more marathon to complete tomorrow before finally finishing the race.