Amid warnings from other world leaders—and planned protests outside—Mahmoud Ahmadinejad addressed the United Nations General Assembly on Wednesday, his last speech in front of the world body as president of Iran.

The outspoken Iranian leader called for a "new world order," criticizing capitalism and the United States and Europe for "trampling on the rights of others" and contributing to global poverty and humanitarian failures.

"The history of mankind is marked with failures," Ahmadinejad said in a speech that was not attended by the U.S. and Israeli delegations in protest.

Ahmadinejad ticked off a long list of those failures—including environmental atrocities, the killing of "millions" of people in U.S.-led wars in Iraq and Afghanistan, the "throwing of [Osama bin Laden's body] into the sea" without witnesses or a trial, and a world media sympathetic to "Zionism"—before lamenting "how beautiful and pleasant our lives and the history of mankind would have been" without them.

"Poverty is on the rise, and the gap is widening between the rich and the poor," Ahmadinejad said, blaming the "current world order, founded on materialism, that aims to monopolize power, wealth, science and technology for a limited group.

"There is no doubt that the world is in need of a new order and fresh thinking," he said. "An order that aims to revive human dignity and believes in peace and welfare for all walks of life.

"Do people that spend hundreds of millions on election campaigns have the interests of people of the world at heart?" Ahmadinejad asked.

[Slideshow: Images from the U.N. General Assembly]

"Capitalism is bogged down in a self-made quagmire," he said, calling for a U.N. restructuring.

Ahmadinejad's speech came a day after President Barack Obama issued a stern warning to Iran over its nuclear program.

"Make no mistake," the president said. "A nuclear-armed Iran is not a challenge that can be contained. It would threaten the elimination of Israel, the security of Gulf nations and the stability of the global economy."

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On Tuesday, Ahmadinejad scoffed at the notion of an Iranian nuclear buildup.

"A nuclear weapon? For what? For what purpose?" Ahmadinejad said in an interview with the Associated Press. "Why would we do that? What would we use it for?"

The leader of Iran—who refuses to refer to Israel by name—also dismissed talk of a U.S. or Israeli military strike on Tehran's nuclear facilities, Agence France-Presse said.

"Uncultured Zionists that threaten the Iranian nation today are never counted and are never paid any attention in the equations of the Iranian nation," Ahmadinejad said earlier this week.

Demonstrators who have been protesting this week outside the hotel where Ahmadinejad is staying were expected to be outside the U.N. while he spoke.

In a statement issued before Ahmadinejad's speech, Erin Pelton, spokeswoman for the U.S. Mission to the United Nations, said: "Over the past couple of days, we've seen Mr. Ahmadinejad once again use his trip to the U.N. not to address the legitimate aspirations of the Iranian people but to instead spout paranoid theories and repulsive slurs against Israel."