Sir Ranulph Fiennes completes desert race Marathon des Sables

Veteran British adventurer Sir Ranulph Fiennes has become the oldest Briton to complete the gruelling desert endurance event the Marathon des Sables.

The 71-year-old crossed the finish line in Morocco at 19:37 BST after running 159 miles (256km) over six days in temperatures in excess of 50C (122F).

He was almost forced to pull out on Thursday owing to heart problems caused by the physical exertion.

His challenge raised nearly £1m for the cancer charity Marie Curie.

'Dangerously close'

During Friday's final stage of what has been dubbed "the toughest footrace on earth" Sir Ranulph, from Exmoor in Somerset, ran for 10 hours.

After crossing the finish line, he said: "I don't feel good, my back is bad. Luckily I've had a load of pain killers. Without them it would have been even more difficult.

"I never thought I wouldn't make it but there were points where I thought the camels, who walk at the rear sweeping up those who are too slow, were getting dangerously close."

He also thanked those who had donated to his cause.

Sir Ranulph has run a total of 156 miles (256km) in six days

'More hellish than Hell'

There were fears Sir Ranulph, who trained for the race on sand dunes in south Wales, might not finish the event after the 56-mile (91km) fourth stage, which saw him run for more than 30 hours on just one hour of sleep.

He described that penultimate day's walk as "more hellish than Hell".

He has previously suffered two heart attacks and underwent a double heart bypass in 2003.

Dr Jane Collins, chief executive of Marie Curie said: "We'd like to say a huge congratulations and thank you to Sir Ranulph Fiennes.

"It was clearly an incredibly difficult physical and mental challenge and he proves that with sheer determination, anything is possible.

"His never failing commitment to finish the race and raise as much money as possible has simply been fantastic.

"We hope he inspires others to take on their own challenge for Marie Curie and help us care for more people living with a terminal illness."

Sir Ranulph had medical treatment for his back pain prior to the final race stage on Friday

There were fears the Somerset adventurer would be not able to finish due to heart problems

Sir Ranulph has previously raised £6.3 million for the charity.

In 2007, he climbed the north face of the Eiger for the charity and in May 2009, at the age of 65, he became the oldest Briton to climb to the summit of Mount Everest.