Ariel Shaeban, right, an Iranian immigrant now residing in New York, screams at pro-Iranian protesters outside the campus of Columbia University during a speech by Iranian President Mahmoud Ahmadinejad on Monday in New York.

New York ? Iranian leader Mahmoud Ahmadinejad defended Holocaust deniers and raised questions about who carried out the Sept. 11 attacks in a tense showdown Monday at Columbia University where the school’s head introduced the visitor by calling him a “petty and cruel dictator.”

Ahmadinejad, appearing shaken by what he called “insults” from his host, sought to portray himself as an intellectual and argued that his regime had respect for reason and science. But the former engineering professor soon found himself drawn into the type of rhetoric that has alienated American audiences in the past.

He provoked derisive laughter by responding to a question about Iran’s execution of homosexuals by saying: “In Iran we don’t have homosexuals like in your country … I don’t know who’s told you that we have this.”

At times, however, he drew audience applause, such as when he bemoaned the plight of the Palestinians.

But his first stab was at Columbia’s president, Lee Bollinger, who said in his introduction of Ahmadinejad: “Mr. President, you exhibit all the signs of a petty and cruel dictator.”

Ahmadinejad said Bollinger’s opening was “an insult to information and the knowledge of the audience here.”

“There were insults and claims that were incorrect, regretfully,” Ahmadinejad added, accusing Bollinger of falling under the influence of the hostile U.S. press and politicians.

Appearing agitated at times, Iran’s president often declined to offer the simple answers the audience sought, responding instead with his own questions or long discursions about history and justice.

Aggressive introduction

Bollinger opened by aggressively taking on Ahmadinejad’s past statements about the Holocaust.

“In a December 2005 state television broadcast, you described the Holocaust as the fabricated legend,” he said. “One year later, you held a two-day conference of Holocaust deniers.”

Bollinger said that might fool the illiterate and ignorant.

“When you come to a place like this, it makes you simply ridiculous. The truth is that the Holocaust is the most documented event in human history,” he said.

Ahmadinejad denied he had questioned the existence of the Holocaust.

“Granted this happened, what does it have to do with the Palestinian people?” he said.

But Ahmadinejad went on to say that he was defending the rights of European scholars, an apparent reference to a small number who have been prosecuted for denying or minimizing the Holocaust.

“There’s nothing known as absolute,” he said.

Questioning 9/11

Asked why he had asked to visit the World Trade Center site – a request denied by New York authorities – Ahmadinejad said he wanted to express sympathy for the victims of the Sept. 11 attacks.

Then he appeared to question whether al-Qaida was responsible, saying more research was needed.

“If the root causes of 9/11 are examined properly – why it happened, what caused it, what were the conditions that led to it, who truly was involved, who was really involved – and put it all together to understand how to prevent the crisis in Iraq, fix the problem in Afghanistan and Iraq combined,” Ahmadinejad said.

‘Simply inappropriate’

Bollinger drew strong criticism for inviting Ahmadinejad to Columbia and had promised tough questions in his introduction. But the stridency of his attack on the Iranian leader took many by surprise.

“You are either brazenly provocative or astonishingly uneducated,” Bollinger told Ahmadinejad about the leader’s Holocaust denial. “Will you cease this outrage?”

Bollinger’s introduction was “very harsh,” said Hamid Dabashi, a professor of Iranian studies at Columbia University.

“Inviting him and then turning around and alienating and insulting an entire nation whose representative this man happens to be is simply inappropriate,” Dabashi said.

Remarks

In Iran, Ahmadinejad’s appearance at Columbia could be seen on Arabic satellite channels and state television’s Arabic-language service, but it did not appear on channels that broadcast in Farsi, the language of Iran.

During his prepared remarks, the Iranian president did not address Bollinger’s accusations directly, instead launching into quotes with the Quran and criticism of the Bush administration and past American governments, from warrantless wiretapping to the atomic bombings of Hiroshima and Nagasaki in Japan.

He said the Holocaust has been abused as a justification for Israeli mistreatment of the Palestinians.

“Why is it that the Palestinian people are paying the price for an event they had nothing to do with?” Ahmadinejad asked.

He closed his prepared remarks with a terse smile, to applause and boos, before taking questions from the audience.

Ahmadinejad claimed women have tremendous rights in Iran and insisted his country does not believe in nuclear weapons.

Asked about his country’s nuclear intentions, he insisted the program is peaceful, legal and entirely within Iran’s rights, despite attempts by “monopolistic,” “selfish” powers to derail it. “How come is it that you have that right, and we can’t have it?” he added.