The IAEA is a United Nations organization that verifies compliance with safeguards mandated by the nuclear Non-Proliferation Treaty (NPT), of which Iran is a member.

The IAEA's 35-nation board of governors, which meets every three months, regularly reviews compliance with safeguards and can appeal to the Security Council to deal with countries that do not comply.

The Security Council can adopt punishing economic sanctions if necessary.

The IAEA board is not due to meet until September but can be called into emergency session on the demand of any one of its members, agency spokeswoman Melissa Fleming said.

The foreign ministers of Britain, France and Germany issued a joint warning to Iran Tuesday, saying they "would have no option but to pursue other courses of action," a clear reference to the Security Council, if the Islamic Republic resumed nuclear activities in breach of a deal struck with the European Union.

Fleming said the IAEA has not yet received a request from the European trio, who are all on the agency's board, for an emergency meeting.

If such a demand were made, at least three days would be needed to convene an emergency meeting since "we require 72 hours to call in the resources and to set things up" at IAEA headquarters in Vienna, Fleming said.

She said referring a nation to the Security Council was "the ultimate sanction for the IAEA," which itself has no enforcement powers.

In 2003, the IAEA referred North Korea to the Security Council after the Asian country kicked out agency inspectors and withdrawn from the Non-Proliferation Treaty.

The Council did not impose punitive measures, despite the severity of the case.

The IAEA has also referred countries to the Security Council merely for information purposes, such as Libya in 2004, after Libya had owned up to its non-compliance and agreed to dismantle its nuclear weapons program and cooperate fully with the atomic agency.