The United States has said Iranian plans to hold a conference that will question whether the Nazis used gas chambers to kill Jews during the Holocaust are disgraceful.
Iranian President Mahmoud Ahmadinejad caused outrage last year when he said the Holocaust was a myth.
While he has not repeated the remark, Mr Ahmadinejad has said the Holocaust is open to question.
US State Department spokesman Sean McCormack said the conference is yet another disgraceful act on this particular subject by the regime in Tehran.
