Prince Harry has praised the "staggering determination" of a group of injured veterans attempting to conquer Everest.

The charity Walking With The Wounded launched the ambitious project to put five war-wounded men on the mountain's summit as Harry agreed to be the expedition's patron.

The royal even clambered into an altitude chamber at an event staged in central London to promote the adventure, to experience some of the conditions the group will face during their epic climb. He emerged red faced and slightly out of breath after he was elevated to more than 5,000 metres above sea level during the demonstration.

Harry already has a close connection with the charity as he was patron of its successful bid last year to get a group of unsupported amputees to the geographic North Pole by foot, and even joined them for a number of days on the ice.

Amongst the guests at the launch event was actor Brian Blessed who has attempted to reach the top of the world's highest mountain but failed.

In a speech to the team who will tackle the mountain, Harry, dressed in a top emblazoned with the expedition's logo, said: "Mount Everest - a name to instil fear into the hearts of seasoned mountaineers, isn't that right Brian? Not so for this crop of lunatics with odd numbers of arms and legs but staggering determination."

Harry added: "But this is not just about the men you see before you. It's about the future for many more. The expedition to the Himalayas - of which I am so proud to be patron - is raising money to train and educate those with physical and cognitive injuries suffered in war to manage their transition into civilian employment.

"The premise is quite simple: a job equals security. They have given their all for our security. Security is the very least as a nation we owe them."

The Prince was joined in the altitude camber - a large plastic box with two treadmills - by one of the expedition team, Karl Hinett, a former private in the Staffordshire Regiment who suffered severe burns to his hands, face and arms during a petrol bomb attack on his warrior tank in Basra, Iraq, in 2005.

The pair were wired up to monitors which displayed their pulse rates and the oxygen saturation levels in their blood on screens outside the chamber.