Iran's government spokesman on Tuesday branded the Holocaust a "big lie" created to place the Islamic republic's arch-foe Israel in the Middle East, the state IRNA news agency reported.
"The Holocaust is a concept coming from a big lie in order to settle a rootless regime in the heart of the Islamic world," Gholam Hossein Elham told a conference on Gaza in central Iran's religious city of Qom.
It was not the first time an Iranian official has questioned the massacre of Jews by Nazis in World War II.
Iran does not recognise Israel, and since his election in 2005 President Mahmoud Ahmadinejad has attracted international condemnation by repeatedly predicting that the Jewish state is doomed to disappear.
In late 2005 Ahmadinejad branded the Holocaust a "myth." His comment was followed by a conference in Tehran in 2006 that brought together Holocaust deniers and revisionists.
A mass-circulation Iranian newspaper also staged a controversial cartoon competition on the subject.
In September last year a group of Iranian Islamist students unveiled a book mocking the Holocaust and filled with anti-Semitic stereotypes and revisionist arguments.
The United Nations designated January 27 as international Holocaust memorial day in 2005, marking the date Soviet troops liberated the largest Nazi death camp, Auschwitz-Birkenau, in Poland.