Updated

Iran (search) warned that an Oct. 31 deadline to prove its nuclear aims are peaceful could backfire, suggesting Tehran could become even more secretive instead of opening its program for outside perusal.

The International Atomic Energy Agency's (search) board of governors voted Friday to approve a U.S.-backed resolution imposing the deadline on Tehran to clear up questions about its nuclear program.

Chief Iranian delegate Ali Akbar Salehi then walked out in protest. Iranian officials had repeatedly warned that imposing a deadline and insisting on other tough language in the resolution would aggravate nuclear tensions.

"We will have no choice but to have a deep review of our existing level and extent of engagement with the agency," Salehi said, suggesting that Tehran might reduce or even break off links — moves that would doom inspection attempts.

North Korea, another country that had come under scrutiny, made good on a threat to break tries with the U.N. nuclear agency last year. In November, it pulled out of the Nuclear Nonproliferation Treaty (search).

If the next board meeting in November determines that Iran has not complied with the treaty banning the spread of nuclear arms, the noncompliance must reported to the U.N. Security Council, where reaction could range from formal criticism to economic sanctions.

Ahead of the invasion that toppled Saddam Hussein (search), the Bush administration argued that Iraq had defied IAEA inspectors and hid plans to make nuclear and other weapons of mass destruction. But diplomats said there were few parallels, with any finding of Iranian noncompliance unlikely to go beyond political and economic pressure.

Salehi — whose decision to walk out in protest was a first in recent agency memory — accused the United States of provoking the protest.

"At present, nothing pervades their appetite for vengeance, short of confrontation and war," he told the meeting. "It is no secret that the current U.S. administration ... entertains the idea of invasion of yet another territory as they aim to re-engineer and reshape the entire Middle East region."

"We reject the ultimatum in this draft," he said.

The resolution, submitted by Australia, Canada and Japan, called on Iran to "provide accelerated cooperation" with agency efforts to clear up questions about Tehran's nuclear program.

It also urged Iran to "ensure there are no further failures" in reporting obligations and called on it to "suspend all further uranium enrichment-related activities, including the further introduction of nuclear material" into a facility where U.N. nuclear agency inspectors found traces of weapons-grade enriched uranium.

The United States and other Western countries accuse Iran of working on a secret nuclear weapons program. They had been pushing for a resolution finding Iran in noncompliance, but gave up because of lack of support among board members.

Chief U.S. delegate Kenneth Brill said the threat by Iran to cut or end cooperation with the IAEA only "suggests they have something to hide that they do not want to come to light."

In Washington, State Department deputy spokesman Adam Ereli welcomed the board's action.

If Iran fails to answer agency questions by Oct. 31, "That would constitute further evidence of its ongoing activities to conceal its clandestine activities and its clandestine nuclear weapons program," he said.

An IAEA report to the board noted that traces of highly enriched, weapons-grade uranium were found at an Iranian nuclear facility, and said tests run by Iran make little sense unless the country is pursuing nuclear weaponry.

Tehran insists its nuclear programs are designed to generate electricity and that its equipment was "contaminated" with enriched uranium by a previous owner.

IAEA director general Mohamed ElBaradei (search) expressed confidence that Iran would comply with the agency.

"I think the board is sending a very powerful message of support to the agency's work, to my work," he said after Friday's session. "It's also sending a very powerful message to Iran that they need to cooperate fully and immediately and to show complete transparency."