Tehran threatened it might retaliate by reconsidering plans to suspend its uranium enrichment.
In harsh language, the resolution approved by the 35-member board of governors of the International Atomic Energy Agency "deplores" that "Iran's cooperation has not been as full, timely and proactive as it should have been," and notes "with concern that after almost two years" since Iran's undeclared program came to light, "a number of questions remain outstanding."
Even as the IAEA was finishing the resolution criticizing Iran, diplomats speaking on condition of anonymity said the agency was looking into accusations that Iran was razing parts of a restricted area next to a military complex in a Tehran suburb.
Satellite photos showed that several buildings had been destroyed and topsoil had been removed at Lavizan Shiyan, previously disclosed as a possible site for weapons of mass destruction, one diplomat said.
Iran's chief delegate to the Vienna meeting of the IAEA's board of governors, Hossein Mousavian, denied a cover-up and told The Associated Press the IAEA was free to see the site. "There is nothing there," he said.
The resolution submitted by three European powers — France, Germany and Britain — was a product of days of diplomatic maneuvering over the right wording. Iran tried to tone it down.
IAEA Director General Mohamed ElBaradei said the resolution "calls in very explicit terms on Iran to accelerate its cooperation with the agency." Asked whether a deadline was needed to force Tehran to comply, he told reporters the board "expects these issues to come to a close in the next few months."
Undersecretary of State John R. Bolton said Washington was "very pleased."
"The results will keep Iran's nuclear program and its efforts to deceive and obstruct IAEA inspectors at the center of international attention for quite some time," he said in a statement to The Associated Press.
Though the resolution does not give a deadline, it states that it is essential for Iran to deal with issues "within the next few months."
It does not contain a "trigger mechanism" — a clause sought by Washington that could send the Iran case to the U.N. Security Council for violating the Nuclear Nonproliferation Treaty.
But a Western diplomat familiar with the U.S. position said the Americans were content because they "feel this ... helps tee (Iran) up for Security Council action" at the next board meeting in September. He did not elaborate.
"Intense negotiations this week softened criticism of Iran and broke the stalemate which had Iran threatening to develop its nuclear weapons capability," said CBS News foreign affairs analyst Pamela Falk, "but being that close to the brink makes everyone nervious and makes further inspections a must."
In veiled condemnation of the United States, which insists Tehran has nuclear weapons ambitions, Iranian delegate Amir Zamaninia told the meeting that the tone of the resolution was affected by "wild and illusionary allegations of a secret Iranian nuclear weapons program."
He warned that his country was reviewing its "voluntary confidence-building measures," an indication that Iran might rethink the suspension of its uranium enrichment activities. Enrichment can produce fuel for electricity or weapons-grade uranium for warheads.
While Tehran maintains that it is interested only in generating electricity, the United States claim Iran's nuclear activities are a smoke screen for a weapons program.
Most of the still-unanswered questions in Iran focus on the sources of traces of highly enriched uranium found at several sites in Iran, and the extent and nature of work on the advanced P-2 centrifuge, used to enrich uranium.
Tehran says the minute finds of highly enriched uranium were not produced domestically but were inadvertently imported in purchases through the nuclear black market — an assertion the agency has not yet proven.
Asked about Lavizan Shiyan, ElBaradei said his agency would "like to … clarify" suspicions about the site but added that the IAEA for now was withholding judgment on whether there had been undeclared nuclear activities there. He said he hoped inspectors could go to the site and report their findings to the next scheduled board meeting in September.