While it is important to get medical attention for injured soldiers as soon as possible, it is often difficult and dangerous for their comrades to reach them and carry them back.

The 6ft tall Bear can cross bumpy ground without toppling thanks to a combination of gyroscopes and computer controlled motors to maintain balance.

It is also narrow enough to squeeze through doorways, but can lift 135kg with its hydraulic arms in a single smooth movement, to avoid causing pain to wounded soldiers.

While the existing prototype slides its arms under its burden like a forklift, future versions will be fitted with manoeuvrable hands to gently scoop up casualties.

The Bear is controlled remotely and has cameras and microphones through which an operator sees and hears.

It can even tackle stairs while carrying a human-sized dummy.

Daniel Theobald, the president of Vecna Technologies, which is developing the robot for the US Army, said: "We saw a need for a robot that can essentially go where a human can. The robot will be an integral part of a military team."

Gary Gilbert, from the US Army's Telemedicine and Advanced Technology Research Centre in Frederick, Maryland, said that the teddy bear appearance was deliberate.

"A really important thing when you're dealing with casualties is trying to maintain that human touch."

Vecna is working on other potential applications for the robot technology - including helping move heavy patients in hospital.