GENEVA (AP) " Dozens of Western diplomats walked out of a U.N. conference and a pair of rainbow-wigged protesters threw clown noses at Iran's president Monday when the hard-line leader called Israel the "most cruel and repressive racist regime."
The United States decried the remarks by Mahmoud Ahmadinejad as hateful " reinjecting tension into a relationship that had been warming after President Barack Obama sought to engage Iran in talks on its nuclear program and other issues.
Ahmadinejad " the first government official to take the floor at the weeklong event in Geneva " delivered a rambling, half-hour speech that was by turns conciliatory and inflammatory. At one point he appealed for global unity in the fight against racism and then said the United States and Europe helped establish Israel after World War II at the expense of Palestinians.
"They resorted to military aggression to make an entire nation homeless under the pretext of Jewish suffering," he said.
Jewish groups had lobbied heavily for a boycott of the conference, warning it could descend into anti-Semitism or other anti-Israel rhetoric, which marred the last such conference eight years ago in South Africa.
The meeting turned chaotic almost from the start when the two wigged protesters tossed the red clown noses at Ahmadinejad as he began his speech with a Muslim prayer. A Jewish student group from France said it had been trying to convey "the masquerade that this conference represents."
One of the protesters shouted "You are a racist!" before he and the other demonstrator were taken away by security.
Ahmadinejad interjected: "I call on all distinguished guests to forgive these ignorant people. They don't have enough information."
During his speech, he accused Israel of being the "most cruel and repressive racist regime" and blamed the U.S. invasion of Iraq on a Zionist conspiracy.
At the first mention of Israel, about 40 diplomats from Britain and France and other European Union countries exited the room.
Most of his remarks were not new but their timing and high profile could complicate U.S. efforts to improve ties with Iran. Alejandro Wolff, the U.S. deputy ambassador to the U.N., denounced what he called "the Ahmadinejad spectacle."
White House press secretary Robert Gibbs, asked by reporters about Ahmadinejad's remarks, replied: "Obviously, the president disagrees vehemently with what was said, as, from some of the video I saw, so did many others."
Gibbs said it proved that the United States was right to boycott the conference. Germany, Italy and at least six other countries also refused to attend the event, which began on the eve of Israel's Holocaust Remembrance Day.
"We call on the Iranian leadership to show much more measured, moderate, honest and constructive rhetoric when dealing with issues in the region, and not this type of vile, hateful, inciteful speech that we all saw," Wolff said at the U.N. in New York.
Later, about 100 members of mainly pro-Israel and Jewish groups tried to block Ahmadinejad's entrance to a scheduled news conference.
In a milder protest, Jewish groups outside the venue read out some of the names of the 6 million who died in the Holocaust.
U.N. Secretary-General Ban Ki-moon met with Ahmadinejad before his speech and said he had counseled the Iranian leader to avoid dividing the conference. Ban later said he was disappointed the speech was used "to accuse, divide and even incite," directly opposing the aim of the meeting.
"It was a very troubling experience for me as a secretary-general," he said. "It was a totally unacceptable situation."
The Israeli Foreign Ministry condemned the speech and Ban's meeting with Ahmadinejad.
"It is unfortunate that U.N. Secretary-General Ban Ki-moon deemed it appropriate to meet with the greatest Holocaust denier of our time," the Foreign Ministry said. "This matter is especially severe, as it took place on the eve of Holocaust Memorial Day."
Ahmadinejad has been praised by some in the Muslim world for his attacks on Israel. The hard-liner has often used international forums to criticize Israel.
Most Muslim delegations in Geneva declined to comment, but Pakistan said the protesters were wrong to interrupt Ahmadinejad.
"If we actually believe in freedom of expression, then he has the right to say what he wants to say," Ambassador Zamir Akram told The Associated Press. "There were things in there that a lot of people in the Muslim world would be in agreement with, for example the situation in Palestine, in Iraq and in Afghanistan, even if they don't agree with the way he said it."
While the speech was interrupted several times by cheers from the large Iranian delegation, it may not be well-received among many others in Iran, which is suffering from high inflation and unemployment partly as a result of its global isolation. Many have criticized Ahmadinejad, who is up for re-election in June, for spending too much time on anti-Israel and anti-Western rhetoric and not enough on the country's economy.
Associated Press writers Bradley S. Klapper and Eliane Engeler in Geneva, and Edith M. Lederer at the United Nations contributed to this report.