The world leaders stressed the need to learn from history.

The Holocaust must not be forgotten by the future generations, they urged, because it was a reminder of man's cruelty to his fellow man.

The international community must work together to ensure such atrocities are never allowed to happen again, the ceremony urged.

Auschwitz survivor Mr Leon Greenman, prisoner number 98288, stands by a mural of the gates of the camp.

Photograph: Ian Waldie/Getty Images