Germany can never forget the horrors of the genocide orchestrated by its ancestors, the German president said marking the 70th anniversary of the Nazi meeting that secured the terrible fate of six million Jews.

President Christian Wulff said the memory of the 20 January, 1942, Wannsee Conference in Berlin, attended by senior Nazi party officials who finalised plans for the Holocaust, should be kept alive.

"We cannot be allowed to forget that this - the unbelievable and unimaginable - actually happened," he said at the villa near where the conference was held.

"This place and the name 'Wannsee' has become a symbol for the bureaucratically organized decision between life worth living and life not worth living, for state-organized extermination, for the planned and official systematic killing of Europe's Jews."

He added: "This place became a place of cold cruelty, a trigger for carrying out systematic genocide, a place of German shame."

The villa is now a museum dedicated to the victims of the Holocaust.

Wulff warned that people who harbour similar views are still in our society.

"It fills us with shame and anger," he said.

"We will do everything to ensure that terror and the murderous hatred of others never finds a place in Germany again."