Iran on Monday opened a two-day international conference to discuss the Holocaust, a move that has sparked widespread controversy.

But Iran has insisted that the conference was aimed at providing a venue for free discussions on "a historical issue" and discussing the scale of the Holocaust and whether the Nazis really used gas chambers to kill Jews.

"The objective of the conference is not to deny or prove the Holocaust. Its main aim is to create an atmosphere for thinkers to discuss freely the Holocaust," Iranian Foreign Minister Manouchehr Mottaki told the opening ceremony.

There was "no logical reason for opposing this conference," Mottaki said.

The conference, dubbed "Study of the Holocaust: A Global Perspective," was initiated by Iranian President Mahmoud Ahmadinejad, who had called the Holocaust, in which 6 million Jewswere killed, a "myth."  

The Iranian Foreign Ministry's Institute for Political and International Studies (IPIS), which organized the conference, said67 researchers from 30 countries would attend the meeting.

"Some people who had been asked to attend refused, saying it aims to deny the Holocaust. Others assumed the international conference was politically motivated and were reluctant to attend," IPIS chief Rassoul Moussavi said.

"Officials in charge of organizing the conference do not intend to deny or confirm it (the Holocaust). The duty of the IPIS is to create a suitable atmosphere for discussing historical issues," he said.

UN Secretary-General Kofi Annan has strongly opposed any attempt to question or deny the Holocaust, UN spokesman Stephane Dujarric said on Thursday, underlining that Annan will deeply deplore any conference whose purpose is to question or deny the reality of the Holocaust.

The conference has also aroused criticism from the United States and Germany.

U.S. State Department spokesman Sean McCormack said on Friday that "this meeting is really focused on highlighting those people who deny that there was, in fact, a Holocaust."

"In that regard, it's just yet another disgraceful act on this particular subject by the regime in Tehran," he added.

The German Foreign Ministry called in Iran's top envoy in Berlin on Friday in protest against the conference.