Prisoners at Sachsenhausen who were given the drug, code-named D-IX, were forced to march in circles carrying 20kg packs. They were able to march 55 miles without resting.

The German news magazine Focus quoted an eye-witness report by a prisoner who wrote: "At first the members of the punishment battalion whistled and sang songs. [But] most of them had collapsed after the first 24 hours."

The pills contained a mix of cocaine, the amphetamine pervitin and a morphine-related painkiller, according to Focus, which said that Nazi scientists began experimenting with the drug in 1944.

It was hoped the drug would give soldiers almost unlimited fighting powers at a time when the German armies were in retreat.

The researcher Wolf Kemper, who uncovered the project, said: "The aim was to use D-IX to redefine the limits of human endurance."

Nazi doctors were enthusiastic about the results, and planned to supply all German troops with the pills, but the war ended before D-IX could be put into mass production.

Hitler was against drug use, particularly condemning the use of cocaine, a popular society drug in the 1920s that the Nazis called "devil's stuff".

But the Third Reich did not have the same scruples when it came to military use of drugs. Amphetamines were mass-produced for use at the front, the same article reported.

Despite doctors' warnings about their side-effects, amphetamine pills were in every first-aider's kit to give to exhausted soldiers.