The U.S. delegation "has decided not to attend" the speech to be delivered by Iranian President Mahmoud Ahmadinejad before the United Nations General Assembly, Erin Pelton, spokeswoman for the U.S. Mission to the United Nations, said in a statement Wednesday.

"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," Pelton said.

The Iranian leader's addresses to the assembly have often generated controversy in the past. The tensions over Tehran's disputed nuclear program and speculation over a possible attack on Iran by Israel offer ample material for drama this time around.

In previous years, several delegations have walked out during Ahmadinejad's speeches, which have assailed the United States and criticized countries that he said used the Holocaust as an "excuse to pay ransom to Zionists."

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He will be taking to the podium Wednesday, a day after President Barack Obama told the assembly that while Washington remains committed to a diplomatic solution to Iran's nuclear program, the United States "will do what we must to prevent Iran from obtaining a nuclear weapon."

Iran says its nuclear program is for peaceful purposes and to fill energy shortages, but Western leaders believe Tehran is an aspiring armed nuclear power. U.N. inspectors have also expressed doubts about the program's aims.