WASHINGTON (AP) _ A half-century after the liberation of the Nazi concentration camps, the faces of those who suffered ``implore us to never forget what happened,'' Postmaster General Marvin Runyon said Tuesday.

Runyon presented an enlargement of the artwork from its Holocaust commemorative stamp to the trustees of the U.S. Holocaust Memorial Museum.

The stamp, showing the faces of concentration camp survivors peering from behind barbed wire, was released in September as part of a World War II set.

``When the Allies liberated the Holocaust survivors they came face to face with those who had peered into the very heart of ... darkness,'' Runyon said. ``A half-century later those faces still speak.''

Rep. Ben Gilman, R-N.Y., said the stamp and the museum ``will help ensure that future generations will not forget the Holocaust.''

``Stamps have great power,'' said Sen. Carl Levin, D-Mich. ``This stamp will contribute to your work making sure the American people are told about the Holocaust.''

The stamp's depiction of the survivors ``is a tribute to the triumph of the human spirit over pure evil,'' added David Fineman of the Postal Service's governing board.

The museum in Washington honors the memory of the 6 million Jews killed by the German Nazis.