In a statement endorsed by the United States and other agency members, the board of the International Atomic Energy Agency said it expected Iran "to grant the agency all access deemed necessary by the agency" to defuse suspicions that Tehran was operating a clandestine nuclear weapons program.
The statement stopped short of demanding Iran accept such inspections but urged the country to look "positively" at signing and ratifying a protocol in addition to its present commitments that would give the agency more inspection powers.
The statement also "encouraged Iran…not to introduce nuclear material" at its Natanz enrichment plant pending the resolution of concerns about what it planned to do with any enriched fuel — normally a component of nuclear warheads.
"Iran should continue to be fully transparent," said Mohamed Elbaradei, head of the International Atomic Energy Agency, in announcing that the board had reached consensus on the statement after days of demanding negotiations. "We still have a lot of work to do."
The statement was a compromise designed to satisfy both Iran, which has denied that it was planning to make nuclear weapons, and the United States, which accuses Tehran of such activity.
"We are happy," with the statement said Ali Akbar Salehi, Iran's delegate. No United States comment was immediately available, but language in the statement expressing displeasure with Tehran's failure to come clean on nuclear activities was expected to please Washington.
Suspicions about the nuclear program prompted ElBaradei to visit Iran in February.
His report revealed that Iran failed to declare the importation of a small amount of nuclear material and its subsequent processing to a point short of that needed for an explosive device.
The report also revealed Iran was building a heavy water production plant, as well as another undisclosed facility. Heavy water is used in nuclear power plants and can be used to produce plutonium for weapons.
Thursday's warning to Iran emerged a day after the United States ratcheted up pressure on the Islamic country with comments in Vienna and Washington.
Kenneth Brill, the U.S. ambassador to the IAEA, chastised Iran Wednesday in a pointed statement delivered to the agency's board during a three-hour debate that featured 23 speeches.
"Can the IAEA or anyone else be confident under these circumstances that there are no other clandestine facilities that have yet to be revealed?" Brill asked.
President Bush, meanwhile, urged the international community to "come together to make it very clear to Iran that we will not tolerate construction of a nuclear weapon."
The president said he and other world leaders would not tolerate nuclear weapons in Iran. But he gave no indication Wednesday that Iran might face military action under his policy allowing pre-emptive attacks where he sees threats.
In Tehran, Iranian President Mohammad Khatami said that his country was not trying to build nuclear weapons. He repeated that Iran was prepared to allow unfettered inspections by the nuclear watchdog agency but expected the international community to recognize Iran's right to acquire advanced peaceful nuclear technology.
"We confidently declare that we are not after nuclear weapons," Khatami said. "Actually we don't believe that atomic weapons can bring security to a nation against countries possessing this kind of weapons."
Iran insists its nuclear program is intended to produce electricity, which will be needed as oil supplies decline.
The United States had wanted IAEA to declare Iran in violation of the Nuclear Nonproliferation Treaty. The matter could then be sent to the U.N. Security Council for possible action.
The compromise language reflected the fact that the United States had met with difficulties in rounding up support for a tough resolution condemning Iran.
Nonaligned countries like Malaysia said the IAEA report "does not imply noncompliance." Others did not want to risk strengthening religious hard-liners, diplomats said. Russia, which is helping Iran build a nuclear power plant, said a resolution was not needed now.
The nuclear dispute is just one area of recent tension between Iran and the United States.
Since the end of the war in neighboring Iraq, the U.S. has accused Iran of stoking anti-American sentiment among Iraqi Shiites and harboring al Qaeda members linked to last months bomb attacks in Saudi Arabia.
For the past two weeks, students have protested against the ruling theocracy in Tehran, clashing violently with hard-line vigilantes. The U.S. government has signaled solidarity with the students.
Khatami said Wednesday that American support for student-led protests only serves to unite his country against the United States.