The governing board of the U.N. nuclear watchdog voted overwhelmingly Friday to censure Iran and demand that the Islamic Republic immediately stop building a nuclear facility that had been kept secret until recent months.
The 25-3 vote by the 35-member board of the International Atomic Energy Agency (IAEA) won rare support from Russia and China, and drew praise from the White House and rebuke from Tehran.
The resolution demanded Iran shut down a newly revealed nuclear facility near Qom until further questions have been answered.
Iran admitted the facility's existence in September, at least two years into its construction, shocking IAEA inspectors. Western diplomats said Iran was forced to come clean after learning the site had been detected by their spy services.
Officials in Tehran called Friday's resolution "a historic mistake" and threatened to curtail the country's cooperation with the IAEA.
Iran's chief representative to the Vienna, Austria-based agency, Ali Asghar Soltanieh, declared that his country would resist "pressure, resolutions, sanction(s) and threat of military attack."
"Neither resolutions of the board of governors nor those of the United Nations Security Council ... neither sanctions nor the threat of military attacks can interrupt peaceful nuclear activities in Iran, even a second," he told the closed-door meeting, in remarks made available to reporters.
But major nations led by the U.S. supported the move and hinted that sanctions might be sought against Iran.
"Today's overwhelming vote ... demonstrates the resolve and unity of the international community with regard to Iran's nuclear program," White House press secretary Robert Gibbs said. "It underscores broad consensus in calling upon Iran to live up to its international obligations and offer transparency in its nuclear program."
Mr. Gibbs said the vote "also underscores a commitment to strengthen the rules of the international system, and to support the ability of the IAEA and U.N. Security Council to enforce the rules of the road, and to hold Iran accountable to those rules."
British Prime Minister Gordon Brown called the resolution "the strongest and most definitive statement yet made by the countries who are very worried about nuclear ambitions on the part of Iran."
Nations were "absolutely clear that Iran has misled the international community," Mr. Brown said at a Commonwealth summit in Trinidad. "[They are] sending the clearest possible signal to Iran that they should desist from their nuclear plans, that the world knows what they are doing and trying to do, and that they should accept the offers that have been made."
Iran claims its nuclear program is meant for peaceful purposes. The U.S. and other Western nations think Iran aims to develop nuclear weapons.
The IAEA resolution criticized Iran for defying a U.N. Security Council ban on uranium enrichment - the source of both nuclear fuel and the fissile core of warheads.
The resolution says the IAEA cannot confirm that Iran's nuclear program is exclusively for peaceful uses and that the agency has "serious concern" about the nation possibly hiding a military nuclear program.
The resolution was moved by the five permanent members of the U.N. Security Council - the United States, Russia, China, Britain and France - and Germany.
"Six nations ... for the first time came together ... [and] have put together this resolution we all agreed on," the Associated Press quoted Glyn Davies, the chief U.S. delegate to the IAEA, as telling reporters. "That's a significant development."
The new support from Russia and China is particularly significant since both have watered down or even blocked previous rebukes in the U.N. Security Council. The two are also active trading partners with Iran, particularly in the oil markets.
The three nations voting against the resolution were Venezuela, Malaysia and Cuba. Six countries - Afghanistan, Brazil, Egypt, Pakistan, South Africa and Turkey - abstained. Azerbaijan missed the ballot.
Mr. Gibbs said the U.S. supports efforts to help Iran use nuclear power in a positive way.
"The United States has strongly supported the [agency's] director general's positive proposal to provide Iran fuel for its Tehran Research Reactor - a proposal intended to help meet the medical and humanitarian needs of the Iranian people while building confidence in Iran's intentions," he said. "The United States has recognized Iran's right to peaceful nuclear energy and remains willing to engage Iran to work toward a diplomatic solution to the concerns about its nuclear program, if and only if Iran chooses such a course."
Betsy Pisik contributed to this report from the United Nations.