Iran's foreign minister has rejected criticism of a two-day conference being held in Iran to examine whether the Holocaust actually happened.
Iran's foreign minister dismissed Western criticism as "predictable"
Manouchehr Mottaki told participants the event did not seek to confirm or deny the Holocaust, but rather to allow people to "express their views freely".
Israel's prime minister has condemned the gathering as "a sick phenomenon".
President Mahmoud Ahmadinejad has questioned the scale of the Holocaust, in which six million Jews died.
According to the foreign ministry in Tehran, 67 researchers from 30 countries are attending the conference in Iran, which is home to 25,000 Jews.
Participants include a number of well-known "revisionist" Western academics. American David Duke, a former leader of the Ku Klux Klan, is to present a paper.
But a small group of Jewish rabbis are also there. One, British Rabbi Ahron Cohen, said he had come to the conference to put the "Orthodox Jewish viewpoint" across.
"We certainly say there was a Holocaust, we lived through the Holocaust. But in no way can it be used as a justification for perpetrating unjust acts against the Palestinians," he said.
His group, Neturei Karta, believes the very idea of an Israeli state goes against the Jewish religion.
Neturei Karta's views are regarded with abhorrence by most other Orthodox Jews, according to Rabbi Jeremy Rosen of the Yakar centre in London.
"And I think, frankly, even among the Hasidic world, by and large Neturei Karta are regarded as freaks," the Orthodox rabbi told the BBC News website.
'Express views freely'
Opening the conference, Mr Mottaki said the aim of the conference was "not to deny or confirm the Holocaust".
"Its main aim is to create an opportunity for thinkers who cannot express their views freely in Europe about the Holocaust," he said.
Mr Mottaki dismissed foreign criticism as "predictable", telling delegates there was "no logical reason" to oppose the conference.
Australian Fredrick Toeben, jailed in Germany for incitement and insulting the memory of the dead
Frenchman Robert Faurisson, convicted in France under Holocaust denial laws
Frenchman Georges Thiel, convicted in France under Holocaust denial laws
American David Duke, a former KKK leader and white supremacist
In a recorded address broadcast to the nation, President Ahmadinejad questioned why the West would not allow "any investigation" into the Holocaust.
Mr Ahmadinejad has repeatedly downplayed the extent of the Holocaust, describing it as a myth used to justify the existence of Israel and oppression of the Palestinians. He has called for Israel to be dismantled.
But in a number of European countries - including Germany, Austria and France - it is illegal to deny the Holocaust. An Austrian court jailed Briton David Irving for three years on charges of Holocaust denial.
Israel's Prime Minister Ehud Olmert condemned the conference as "a sick phenomenon that shows the depths of hatred of the fundamentalist Iranian regime".
Norbert Lammert, president of the German parliament, sent a letter to Mr Ahmadinejad criticising the event.
"I condemn any attempt to offer anti-Semitic propaganda a public forum under the pretext of scientific freedom and objectivity," he wrote.
Some Jewish rabbis are at the conference to put their views across
A number of prominent Holocaust historians are attending a rival gathering taking place in Berlin, backed by the German government, in protest at the Tehran conference.
The US state department last week described the Iranian event as "yet another disgraceful act on this particular subject by the regime in Tehran".
Iran knows this conference is going to cause outrage abroad but it says it wants to test the limits of the West's commitment to freedom of speech, says the BBC's correspondent in Tehran, Frances Harrison.
Iran is drawing a parallel with the Danish cartoons depicting the Prophet Muhammad, which provoked outrage in the Islamic world but were defended by Western liberals, she says.
Iran's one Jewish MP, Morris Motamed, told the BBC he opposed the conference.
"Holding this conference after having a competition of cartoons about the Holocaust has put a lot of pressure on Jews all over the world and it can give nations and governments a very negative impression of Iran," he said.