America and its allies lobbied a key U.N. atomic agency conference on Monday to join them in calling on Iran (search) to disprove that it is running a covert nuclear weapons program.
At unofficial evening meetings, allies Canada and Britain were sounding out other nations on a resolution that would call on Iran to provide full disclosure of its programs.
But Iran's chief delegate, Ali Akbar Salehi, cautioned that too much pressure could backfire.
Iran has hinted it may sign a protocol opening its nuclear programs to full and unfettered inspection by the International Atomic Energy Agency (search).
However, Salehi said that hinges on the outcome of the meeting in Vienna of the IAEA's board of governors.
Earlier he warned of "unexpected or surprising consequences" if board members demanded too much from his country.
Opening the conference of the 35-nation board, IAEA Director-General Mohamed ElBaradei (search) said Iran has been showing increased cooperation. He also said his experts still don't have enough information to determine the nature of Tehran's nuclear activities.
"I would urge Iran in the coming weeks to show proactive and accelerated cooperation ... by providing the agency with a complete and accurate declaration of all its nuclear activities," the U.N. nuclear chief said.
The United States suspects Iran of working on a secret nuclear weapons program. A recent IAEA report to the board, obtained by The Associated Press, said traces of highly enriched, weapons-grade uranium were found at an Iranian nuclear facility.
The report also said Iran was conducting tests that experts say make little sense unless the country is pursuing nuclear weapons.
Tehran insists its nuclear programs are only for generating electricity. It has also said its equipment was "contaminated" with enriched uranium by a previous owner.
Last week the Bush administration decided not to ask the Vienna meeting to endorse a resolution finding Iran in noncompliance of IAEA obligations -- a conclusion that would have brought the matter to the U.N. Security Council.
"There was no other choice but to back down, because that proposal didn't have many countries to go along with it," Salehi said.
Instead, diplomats said, Canada and Britain were sounding out other board member nations on a resolution that would call on Iran to answer questions raised in the report and provide full disclosure of its programs. It also could set a deadline for Tehran to comply, the diplomats said on condition of anonymity.
Diplomats said it was conceivable that the United States would postpone a call to action until the next board meeting in November.
Publicly, the Americans focused on what they said united the Vienna meeting behind them.
In Washington, U.S. State Department spokesman Richard Boucher said most board members agreed that Iran needs to "take steps to cooperate fully and answer all questions. So we'll be working with other members of the board to try to get a resolution that makes that clear in the strongest possible terms."
Only a comprehensive declaration can determine the truth, ElBaradei said Monday, cautioning that much "urgent and essential" work remains to be completed before the agency can draw conclusions.
Some of the information Iran has recently handed over is "piecemeal" or inconsistent with that given previously, he said. Iran should move rapidly toward signing the additional protocol, ElBaradei said, adding: "The more transparency that is provided, the more assurance we can give."
The outcome, he said, "will have major implications for the nonproliferation regime" worldwide.
ElBaradei pressed the Iranians for a list of all imported equipment and components they contend were contaminated as well as their countries of origin, the dates they were acquired and where they have been used or stored. The nuclear agency also needs to know more about Iran's uranium conversion experiments and its testing of gas centrifuges to enrich uranium, he said.
Suspicions about Iran's nuclear activities prompted ElBaradei in February to tour the country's nuclear facilities. Diplomats said he was taken aback by the advanced stage of a project using hundreds of centrifuges to enrich uranium.