It was not immediately clear what the suspension of cooperation would entail.

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Under Iran's Safeguards Agreements with the IAEA, part of its commitments under the Nuclear Nonproliferation Treaty, Tehran is obligated to report to the agency six months before it introduces nuclear material of any kind into any facility.

Beyond that, Tehran has committed itself to informing the agency of any planned new nuclear construction before such construction begins - a commitment it has not always kept. For instance, Tehran delayed informing the agency three years ago that it was building tunnels in the central city of Isfahan to house parts of its uranium enrichment program.

Former UN nuclear inspector David Albright said Sunday's decision could clear the path for Iran to do clandestine nuclear work related to its enrichment program - a possible pathway to nuclear arms.

Albright, whose his Washington-based Institute for Science and International Security tracks Iran's nuclear program, said that Iran may be looking to build a "backup facility" for enrichment that would remain undetected - and safe - in case of attack by the United States or Israel.

IAEA officials were not immediately available for comment.

The new, moderately tougher sanctions on Tehran include banning Iranian arms exports, and freezing the assets of 28 people and organizations involved in Iran's nuclear and missile programs. About a third of those are linked to the Revolutionary Guard, an elite military corps that answers to Tehran leadership.

They also ask countries to restrict travel by the individuals subject to sanctions, as well as arms sales to Iran and new financial assistance or loans to the Iranian government.

The measure also said all sanctions would be suspended if Iran halts enrichment and made clear that the country can still accept a package of economic incentives and political rewards offered last year if it complies with the council's demands.

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