The board of the International Atomic Energy Agency passed a resolution Saturday saying that Iran violated its nuclear treaty obligations by secretly developing a nuclear program. But in a sign of deep division, the agency delayed reporting the matter to the U.N. Security Council, as required by statute.

The resolution states that "the history of concealment of Iran's nuclear activities" had resulted in the "absence of confidence that Iran's nuclear program is exclusively for peaceful purposes." The United States has said Iran has ambitions to develop nuclear weapons, while Iran has said its program is strictly for generating energy.

"The international community is . . . not satisfied with the level of confidence-building measures Iran has so far taken," the IAEA's chief, Mohamed ElBaradei, said. IAEA inspectors have spent more than two years in Iran but have not found proof of a nuclear weapons program there.

But in a rare display of disunity on the 35-member board, which traditionally passes resolutions unanimously, just 22 countries voted in favor of the measure. Twelve countries, including Russia, China, Pakistan, South Africa and Brazil, abstained. One country, Venezuela, opposed it.

Disagreement on the board had forced the European Union and the United States to retreat from their initial demand that Iran be reported immediately to the Security Council, a move that could trigger international sanctions. Instead, the resolution obligates the board to report Iran to the council but leaves open the issue of when.

The vote came after weeks of intense lobbying and a day of frantic, last-minute bargaining that ultimately failed to achieve consensus, illustrating the strength of Iran's evolving alliances, diplomats and analysts said. U.S. and E.U. efforts paid off, however, persuading Russia and China not to vote against the measure, while India changed its early opposition and supported it.

"Iran's activities, its pattern of deception and its confrontational approach are of great concern to the world community," U.S. Ambassador Greg Schulte told reporters after the vote. "We are concerned that these activities pose an increasing threat to international peace and security."

The head of the Iranian delegation, Javad Vaeidi, told reporters that the divided vote demonstrated that the resolution had the backing only of Western countries and was "politically motivated." In a statement to the board, he said Iran was "prepared" to work with the atomic agency to build confidence and increase transparency. But if Iran is reported to the Security Council, Vaeidi added, "we will have no alternative to pursue and preserve our rights."

Iran threatened to begin enriching uranium, a key step in producing nuclear energy and weapons, if the board decided to refer it to the Security Council. Diplomats said Iran would probably deliver a more detailed statement on the matter at the IAEA's general conference Monday.

The resolution adopted Saturday declared that Iran was in "non-compliance" with obligations to the Non-Proliferation Treaty that required it to report its nuclear program, which was developed in secret over 18 years and was exposed about two years ago.

The decision to delay a decision on referring Iran to the council sets the stage for weeks or even months of wrangling among Iran, the E.U. and the United States as they try to woo others to their positions.

The task will become increasingly difficult for the E.U. and the United States because the composition of the board changes next month and several countries, including Cuba and Belarus, that tend to be unfavorable to U.S. policies, will take up seats currently occupied by countries that voted in favor of the resolution Saturday.

Whatever the final outcome, the events this week in Vienna illustrate Iran's diplomatic transformation over the last few years.

Once widely considered a pariah state, Iran has undertaken an aggressive international charm offensive in recent years to win back allies, expand its network of trade partners and boost its influence abroad. The outreach program, initiated by former president Mohammad Khatami, paid off for Iran in Vienna by preventing its immediate referral to the Security Council.

"Khatami fundamentally changed Iran's foreign policy" by repairing relations with many countries, said Ray Takeyh, a Middle East analyst at the Council on Foreign Relations in New York. Khatami led Iran out of its isolation, Takeyh said, and "history will look back and recognize his accomplishments as momentous."

However, the new Iranian president, Mahmoud Ahmadinejad, who was elected this summer, took a more defiant tone on the issue, which did not help his case this week, diplomats indicated.

Iran's reorientation of diplomatic and trade ties, particularly with Russia, China and India, gave Iran important allies in Vienna and could continue to pay off at the United Nations, where Russia and China both wield vetoes on the Security Council, analysts said.

Iran, which has 10 percent of the world's known oil reserves and the second-largest natural gas reserves after Russia, supplied about 14 percent of China's oil imports in 2003. Last fall, China and Iran signed a 25-year, $100 billion deal under which China is expected to buy about 10 million tons of natural gas annually from Iran.

Russia is also heavily involved in helping Iran build a $1 billion nuclear reactor.

Earlier this year, India signed a 30-year, $50 billion deal with Iran to buy 7.5 million tons of natural gas annually. India had expressed its opposition to the E.U. resolution all week, but after intense U.S. lobbying, it voted in favor of finding Iran in non-compliance, and also supported the delayed referral.

Analysts and diplomats said the U.S. position was weakened -- especially among the members of the Non-Aligned Movement, a grouping of countries dating from the Cold War -- by lingering mistrust of the United States in light of the case it presented to the United Nations for going to war in Iraq.

The Non-Aligned Movement "was always critical of the U.S., but they no longer trust that the U.S. is telling the truth," said a diplomat closely following the board's debate.

A critical issue was "sovereignty," said another diplomat here, who like most others spoke only on condition of anonymity because the board's meetings are closed and are supposed to be confidential. "The non-aligned states see the big nuclear powers -- the old colonial states -- calling the shots and limiting their access to nuclear technology," the diplomat said.

Officials said the E.U. and the United States also appeared to lack a concrete strategy for dealing with the Iran case in the Security Council. Diplomats said that Russia, in particular, was concerned that absent a game plan, the matter could escalate out of control.

Staff writer Dafna Linzer in Washington contributed to this report.

The head of the International Atomic Energy Agency, Mohamed ElBaradei, right, talks to Iran's delegate before a board of governors meeting in Vienna.