In tests it demonstrated enormous strength, having a strain density - the amount of energy stored in each gram of a stretched elastic body - 15 times greater than natural muscle.

The device, described as a "soft actuator", was able to lift 1,000 times its own weight, said the researchers whose work is reported in the journal Nature Communications.

Professor Hod Lipson, from the Creative Machines laboratory at Columbia University in New York, said: "We've been making great strides toward making robot minds, but robot bodies are still primitive.

"This is a big piece of the puzzle and, like biology, the new actuator can be shaped and reshaped a thousand ways. We've overcome one of the final barriers to making lifelike robots."

Artificial muscles may not only be used in robots but also sensitive surgical devices and a host of other applications where gripping and manipulation is important.