Washington Correspondent Tom Carver: "Nasa's secret warning"

The American space agency has confirmed that extensive plans were laid in case Neil Armstrong and Buzz Aldrin, the first two men to walk on the moon, were unable to return home.

With no rescue mission planned, their communications to Earth would have been switched off and they would have been left to die or commit suicide, the BBC has learned.

President Richard Nixon even had a speech prepared for the watching world if the Apollo XI lunar landing module could not take off from the moon's surface.

A memo found in America's national archives reveals the extent of emergency planning for the mission by Nasa and the US Government.

Astronauts say they were not told of disaster planning

President Nixon's speech would have read: "Fate has ordained that the men who went to the moon to explore in peace will stay on the moon to rest in peace.

"These brave men, Neil Armstrong and Buzz Aldrin, know there's no hope for their recovery. But they also know there is hope for mankind in their sacrifice.

"For every human being who looks up at the moon in the nights to come will know that there is some corner of another world that is forever mankind."

Greatest danger

The astronauts insist they were never told of any disaster plans.

The greatest danger to the mission's success came from the lunar landing module. Nobody knew whether it would be able to take off from the moon.

Nasa historian Roger Launis said: "Had they not been able to launch the ascent part of the lunar module they would have been stranded on the surface. There was nothing that was realistic that could be done [for them]."

President Nixon's disaster speech has remained secret for 30 years since the two astronauts first set foot on the moon on 20 July 1969.

And instead of a sombre address Mr Nixon was able to congratulate them on a successful mission.