Survivors of Buchenwald joined German leaders on Sunday to remember the Nazi concentration camp's liberation by US troops 60 years ago and to warn that the victims' suffering must never be forgotten.

Some 240-thousand prisoners passed through the camp just outside the city of Weimar between 1937 and 1945.

About 56-thousand died, many worked to death by the Nazis.

Survivors in their 70s and 80s came to Weimar's National Theatre to hear Chancellor Gerhard Schroeder express shame in Germany's name and honour the victims.

"We, who are born after the war, the ambassadors of a different, democratic Germany, will not allow that mischief and violence, that anti-semitism, racism and xenophobia will ever again have a chance in Germany."

With an eye on recent electoral successes by Germany's extreme-right fringe, Schroeder pledged that his country would remain vigilant against neo-Nazi stirrings.