IRAN'S NUCLEAR EFFORT IN HIGH GEAR, U.N. SAYS

The report by Mohamed ElBaradei, head of the International Atomic Energy Agency, confirmed that Iran recently began installing the first of 3,000 gas centrifuges in a heavily fortified, underground chamber at its Natanz plant and that it planned to "bring them gradually into operation by May 2007."

A facility that large, if it functions properly, could produce enough highly enriched uranium in a year to build a nuclear warhead. A senior U.N. diplomat here cautioned that the Iranian schedule was "fairly optimistic" and said that the highly sensitive linked centrifuges, called cascades, may not be operational before the fall.

The six-page report is almost certain to trigger a push by the Bush administration and its European allies for stiffer U.N. sanctions against the Islamic Republic. The intensifying confrontation now moves to London, where major powers will meet Monday to consider a range of actions against Iran.

U.S. Secretary of State Condoleezza Rice, in Berlin, said the United States was determined to "use all available channels and the Security Council" to draft a new resolution aimed at halting Tehran's nuclear activity.

The report "shows that Iran has not changed its behavior, has not changed its views and is continuing on the path of defiance," State Department spokesman Tom Casey said in Washington.

But Russia's U.N. ambassador, Vitaly Churkin, told reporters at the United Nations that sanctions were not a solution. "We should not lose sight of the goal, and the goal is not to have a resolution or to impose sanctions," he said. "The goal is to accomplish a political outcome of this problem."

The Security Council voted unanimously Dec. 23 to give Iran 60 days to close an aboveground test facility at Natanz, where it had begun small-scale uranium enrichment in August. The resolution also required Iran to suspend work at an underground facility at Natanz, halt construction of a nuclear reactor at Arak and freeze other nuclear activities deemed to be worrisome.

ElBaradei's report indicated that the Iranians instead pushed the program into higher gear. The senior U.N. diplomat who discussed the report described it as showing "no progress" in resolving the IAEA's major outstanding concerns.