IAEA Board of Governors, Vienna, Austria

The United Nations nuclear agency says Iran has failed to suspend uranium enrichment as demanded by the U.N. Security Council, as diplomats consider plans for new sanctions against Tehran.

The International Atomic Energy Agency issued a report to the council Thursday saying Iran has expanded uranium enrichment in defiance of the demand. The report clears the way for the council to possibly impose further sanctions on Iran.

On December 23, the U.N. Security Council set a 60-day deadline for Iran to end the enrichment work, and banned Iran's trade in sensitive nuclear and missile technology.

In Washington, U.S. Under Secretary of State Nicholas Burns says he will travel to London on Monday to meet with U.N. Security Council members to begin drafting another sanctions resolution on Iran.

A senior Iranian nuclear official, Mohammad Saeedi, says Iran cannot accept suspending uranium enrichment because that would be contrary to its rights under international treaties.

The White House voiced disappointment over Iran's failure to comply with international demands to stop enriching uranium. But Russia's U.N. Ambassador Vitaly Churkin said his country would prefer not to impose new sanctions on Iran.

The IAEA report says Iran has installed two uranium enrichment networks at its underground nuclear plant in Natanz, but has not fed uranium into the system.

Enriched uranium can be used as fuel for nuclear power, or at more highly enriched levels, to build nuclear weapons.

The United States and other major powers suspect Iran is trying to build nuclear weapons, a charge Tehran denies.