The United States and Israeli used the commemoration of the 75th anniversary of the liberation of the Auschwitz concentration camp to assail Iran, with Prime Minister Benjamin Netanyahu calling it "the most anti-Semitic regime on the planet."
"There will not be another Holocaust," Netanyahu told the Jerusalem gathering on January 23 of more than 40 heads of state and government, blasting what he called "the tyrants of Tehran."
He told the World Holocaust Forum that "we have yet to see a unified and resolute stance against the most anti-Semitic regime on the planet, a regime that openly seeks to develop nuclear weapons and annihilate the one and only Jewish state."
U.S. Vice President Mike Pence called on the international community to "stand strong" against Iran, labeling it as the only country in the world where Holocaust denial is "state policy."
Tehran, which denies it is trying to develop nuclear weapons, also has rejected allegations of anti-Semitism. It claims that while it opposes the Jewish state and supports the Palestinian cause, it has no problem with Jewish people -- including the Jewish minority in Iran itself.
Israeli President Reuven Rivlin earlier thanked world leaders for expressing their "solidarity with the Jewish people" by attending the forum in Jerusalem marking the anniversary of the liberation of Auschwitz
Speaking at the start of the ceremony, Rivlin said that "anti-Semitism does not stop with the Jews," and called anti-Semitism and racism a "malignant disease." He added that "no democracy is immune."
The event at the Yad Vashem Holocaust memorial came amid a spike in anti-Jewish violence in Europe and around the world.
More than 1 million people, most of them Jews, were killed at the Auschwitz-Birkenau concentration camp during Nazi Germany's wartime occupation of Poland. Six million Jews died in the Holocaust.
The Soviet Red Army liberated Auschwitz on January 27, 1945.
Russian President Vladimir Putin, French President Emmanuel Macron, Britain's Prince Charles, U.S. Vice President Pence, and the presidents of Germany, Italy, and Austria are among the more than 40 dignitaries attending the forum, the largest-ever gathering focused on commemorating the Holocaust and combating modern-day anti-Semitism.
Also marking the anniversary was the Saudi head of the Mecca-based Muslim World League (MWL) and some 60 senior Muslim religious and community leaders from across the globe who visited the Auschwitz Holocaust memorial in Poland, calling it "a sacred duty and a profound honor."
MWL Secretary-General Muhammad bin Abdulkarim al-Issa knelt and bowed to the ground as he led Islamic prayers next to the memorial.
David Harris of the New York-based American Jewish Committee, which organized the visit, told AFP it was the "most senior Islamic leadership delegation to ever visit Auschwitz or any Nazi German death camp."
The visit came just days ahead of another set of memorial ceremonies planned for January 27 at the Auschwitz site.
U.S., Israel Blast Iran At Event Marking Anniversary Of Auschwitz Liberation