Iran staged a conference on Monday to debate the Holocaust and question whether Nazi Germany used gas chambers, prompting charges it was encouraging the denial of the killing of 6 million Jews during World War Two. Guests at the government-run event, titled "Review of the Holocaust: Global Vision", included Westerners who have cast doubt on the Holocaust -- some of them from countries that have made it a crime to deny it happened -- as well as a few Jews."The aim of this conference is not to deny or confirm the Holocaust," Foreign Minister Manouchehr Mottaki said. "Its main aim is to create an opportunity for thinkers who cannot express their views freely in Europe about the Holocaust." The two-day conference at a Foreign Ministry institute was inspired by President Mahmoud Ahmadinejad, who since coming to power in August 2005 has sparked international condemnation by terming the Holocaust a "myth" and calling Israel a "tumour".