TEHRAN, Iran -- Iran's president on Wednesday proposed a debate with President Bush at this month's U.N. General Assembly, saying it would be the perfect place for an uncensored discussion that the whole world could watch.

The White House had no immediate response. But it dismissed a previous TV debate proposal from President Mahmoud Ahmadinejad as a "diversion" from serious concerns over Iran's nuclear program.

It was not clear if Iran planned to make a formal proposal through diplomatic channels or whether -- as seemed more likely -- Ahmadinejad's comments were merely another in a line of provocative and often confrontational statements he has made since taking office a year ago.

The overture did seem to signal that Ahmadinejad is determined to try to shape the world debate over Iran's intentions and continue to ignore the West's insistence to curb its nuclear program.

Iran on Wednesday also postponed a tentative meeting with a top European Union official to discuss the nuclear controversy -- a step that seemed to dim prospects the country will make concessions. The United States has said it will push for U.N. sanctions because of Iran's refusal to suspend uranium enrichment as the U.N. had demanded.

Iran insists its nuclear program is for peaceful energy uses only but the United States and some Europeans believe the regime seeks nuclear weapons. On Tuesday, Bush said he would never allow a nuclear-armed Iran because such a government could blackmail the free world.

"I am not going to allow this to happen," Bush said in a speech on terrorism. "And no future American president can allow it, either."