The Vatican has joined Western leaders in criticizing a conference taking place in Iran this week.  The conference’s goal is to question whether the Holocaust actually happened and to discredit the existence of Israel.

Iran's foreign minister opened the controversial two-day conference yesterday by questioning the right of Israel to exist.

The gathering in Teheran, titled "Review of the Holocaust, Global Vision", is being attended by dozens of international guests, including a British anti-Zionist rabbi, reported The Telegraph.

In opening remarks, Manouchehr Mottaki said: "If the official version of the Holocaust is thrown into doubt, then the identity and nature of Israel will be thrown into doubt. If... it is proved that the Holocaust was a historical reality, then what is the reason for the Palestinians having to pay the cost of the Nazis' crimes?"

In a statement released on Tuesday, the Pope called the death of millions of Jews during World War II an "immense tragedy", which must never be forgotten.

"The last century saw an attempt to exterminate the Jewish people, and consequently millions of Jews of all ages and social classes were killed simply because they belonged to that people," the Pope said.

The Vatican statement recalled that a few years ago the Vatican released a document on the Holocaust which expressed "respect" and "compassion" for the tragic fate of the Jewish people during Nazism.

Earlier this year, Pope Benedict XVI condemned anti-Semitism, urging humanity never to forget the horror of the Holocaust. He issued the same message during a visit to the synagogue in Cologne, in August 2005, which was destroyed by the Nazis and rebuilt after the war, as well as on his visit to the concentration camp of Auschwitz in May.

A similar position was affirmed by Pope John Paul II at the Memorial of Yad Vashem in Jerusalem in 2000 and in his message marking the 60th anniversary of the liberation of Auschwitz.

The Holocaust was a "crime that will forever stain the history of humanity," said Pope John Paul II. Its recollection must serve to warn mankind against ideologies that seek to "crush human dignity because of differences in race, color, language or religion."

The conference was initiated by Iran's president, Mahmoud Ahmadinejad, who has described the Holocaust as a "myth" and called for Israel to be wiped off the map, reported The Telegraph. Iran is currently feared to be developing nuclear weapons.

Ahmadinejad told the conference on Tuesday that Israel would soon be “wiped out,” according to Iran’s official Islamic Republic News Agency (IRNA).

"The Zionist regime will be wiped out soon, the same way the Soviet Union was, and humanity will achieve freedom," Ahmadinejad said.

The president has faced the first protests since winning elections 18 months ago. Students lit fireworks and burned his photograph in the audience as he delivered a speech at the Amir Kabir technical university.

Up to 60 protesters chanted "death to the dictator", the IRNA reported. There were no reports of arrests.