VIENNA, Austria —  The U.N. atomic watchdog agency Saturday put Iran just one step away from referral to the Security Council (search) unless Tehran eases suspicions about its nuclear activities in coming months — a move the United States has been pushing for years.

The chief U.S. delegate to the International Atomic Energy Agency (search) hailed the decision, describing it as a wake-up call for Tehran "to come clean" or face the consequences.

But his Iranian counterpart blasted the approval of the resolution and warned of retaliation. Tehran maintains its nuclear program is for generating electricity.

The decision by the 35-nation board represented a victory for Washington, which asserts Iran has nuclear weapons ambitions. For more than two years, it has failed to enlist board support to haul Iran before the council for allegedly violating commitments under the Nuclear Nonproliferation Treaty (search).

"The international community is ... not satisfied with the level of confidence-building measures Iran has so far taken," IAEA chief Mohamed ElBaradei (search) said.

Saturday's decision was far from unanimous, though. Only 22 of the 35 board nations voted for the U.S.-backed European Union (search) motion.

Twelve nations abstained, including Russia and China, which are veto-wielding members of the Security Council, diplomats said. The others were developing nations.

Those supporting the resolution included the United States, European countries, Canada, Australia and Japan. They were joined by India, Peru, Singapore and Ecuador, reflecting some support in the developing nations' camp.

Javier Solana, the chief EU foreign policy official, welcomed the board's "broad support" and said it left the door open to negotiations with Tehran.

Venezuela cast the only vote against. On Friday, Foreign Integration Minister Gustavo Marquez told the state-run Bolivarian News Agency that powerful countries with nuclear energy programs were unfairly keeping others from developing their own.

The resolution called on the board to consider reporting Iran at a future meeting. As grounds, it mentioned noncompliance with the nuclear arms control treaty and suspicions that Iran's nuclear activities could threaten international peace and security.

Diplomats from countries backing the resolution said it set Iran up for referral as early as November, when the board next meets in regular session, unless it dispels international concerns.

Outlining what Iran must do to avoid such action, the draft called on it to give IAEA experts access to nuclear-related documents and sites, suspend all enrichment-related and reprocessing activities and ratify an inspection agreement with the IAEA.

Iran last month resumed uranium conversion — a precursor of uranium enrichment, which can make material for either nuclear fuel or the fissile core of warheads.

The chief U.S. representative to the meeting, Gregory Schulte, said the approval reflected board concern over Iran's "long history of concealment and deception."

In opting for referral, the board is "concerned that Iran's activities pose an increasing threat to international peace and security," Schulte said. "The IAEA has called on Iran to ... come clean."

But Iran's delegation head, Javad Vaeidi, said the vote was evidence "there is no consensus on the way forward." He also warned, "Threat invokes threat."

Tehran already warned Friday that if the resolution was approved, it could respond by starting uranium enrichment — a possible path to nuclear arms — and by reducing IAEA powers to inspect its activities under the additional agreement it signed but had not yet ratified.

Both threats were contained in unsigned letters and shown by a member of the Iranian delegation to ElBaradei, diplomats accredited to the agency said on condition of anonymity because their information was confidential.

The Security Council could impose sanctions if it determines that Iran violated the treaty, but the draft did not mention sanctions in recognition of Russian and Chinese opposition.

A nation's failure to comply with the nonproliferation treaty is automatic grounds for a report to the Security Council under IAEA statutes, and the draft said "Iran's many failures and breaches of its obligations ... constitute noncompliance."

Additionally, Iran's spotty record on cooperating with an IAEA investigation that began in 2002 has led to an "absence of confidence that Iran's nuclear program is exclusively for peaceful purposes," the document said.

That finding puts Iran "within the competence of the Security Council, as the organ bearing the main responsibility for the maintenance of international peace and security," the text said.

The Europeans for years avoided U.S. demands for support in its push to haul Iran before the Security Council. They reluctantly swung behind Washington last month after Tehran effectively walked away from talks with Britain, France and Germany meant to reduce suspicions about its nuclear aims and began uranium conversion.