The White House on Tuesday condemned a gathering of Holocaust deniers in Tehran as "an affront to the entire civilized world as well as to the traditional Iranian values of tolerance and respect."
A statement from press secretary Tony Snow noted the meeting coincided with International Human Rights Week, which renews the pledges of the Universal Declaration of Human Rights drafted in the wake of World War II atrocities.
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"The Iranian regime perversely seeks to call the historical fact of those atrocities into question and provide a platform for hatred," Snow said.
He said the United States will continue to support those in Iran and elsewhere who seek to promote human rights "and will stand with them in their efforts to overcome oppression, injustice and tyranny."
The two-day conference drew 67 participants from 30 countries , some of whom have been prosecuted in Europe for publishing their theories casting doubt on whether 6 million Jews were killed by the Nazis or whether gas chambers were ever used.
The conference touched off indignation across Europe as well, where many countries have made it a crime to publicly disavow the Nazis' systematic extermination of 6 million Jews.
The EU's top justice official condemned the conference as "an unacceptable affront" to victims of the World War II genocide. British Prime Minister Tony Blair denounced it as "shocking beyond belief" and proof of Iranian President Mahmoud Ahmadinejad's extremism.
"I think it is such a symbol of sectarianism and hatred toward people of another religion. I find it just unbelievable, really," Blair said.
"I mean, to go and invite the former head of the Ku Klux Klan to a conference in Tehran which disputes the millions of people who died in the Holocaust ... what further evidence do you need that this regime is extreme?" he added.
David Duke, a former leader of the US white supremacist group, was among those who attended the two-day conference.
French Foreign Minister Philippe Douste-Blazy was interrupted by applause from lawmakers when he told parliament in Paris that the conference showed a resurgence of "revisionist" theories "which are quite simply not acceptable."
The Vatican called the Holocaust an "immense tragedy" and warned the world not to react with indifference to those who challenge its existence.
"The memory of those horrible events must remain as a warning for people's consciences, to eliminate conflicts, respect the rights of all peoples, exhort for peace, truth and justice," the Holy See said in a statement.
