"We have not been seeking referral at this moment to the Security Council," spokesman Richard Boucher said, adding that the United States wanted to see the Vienna-based International Atomic Energy Agency adopt a firm resolution on Iranian compliance.

"We have been pressing for a resolution that's strong, that asks Iran to meet its own commitments, that asks Iran to disclose what it has promised to disclose, that asks Iran to meet the requirements that have been put forward by its membership in the IAEA and put forward by the Board of Governors of the IAEA," Boucher said.

"The United States has felt that it's important for the IAEA to continue its pressure on Iran, to continue its investigation, its inspections, to continue finding things out about this program," he said.

"And as they have continued to do that, including in recent days, including by this revelation that we had in recent days, we think it's appropriate for the board to continue the activity that's going on now," the spokesman added.

Britain, France, and Germany submitted a resolution at the UN atomic agency Thursday calling for a 15-month-old investigation into Iran's nuclear activities to be stepped up and for Tehran to do more to help it complete the probe within a few months, agency officials said.

The United States is concerned Tehran may be seeking to develop a nuclear weapon under the cover of a civilian nuclear program, which the Islamic republic denies.

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