"Iran will complain and say none of these projects are for enrichment or reprocessing, the sensitive technologies that were singled out in the resolution. But the agency is being careful to follow the letter of the Security Council resolution," said Mark Fitzpatrick, a nuclear specialist with the International Institute of Strategic Studies in London.
He said Iran, apparently caught by surprise by the Security Council's unanimous vote in favor of the sanctions resolution in December, has subsequently sought to downplay the measure's potential impact.
"They've been saying it wouldn't amount to anything. Well, here we have an indication that the IAEA says it does amount to something. Here's some projects that have to be stopped," he said. "It will contribute to the psychological discomfort of Iran."
By Kim Murphy, Times staff writer
Iran has set up more than 300 centrifuges at two uranium enrichment sites at its underground Natanz complex, Western diplomats have said.
If confirmed, the centrifuges would be the first of 3,000 that Iran says it is planning to install at the site in the coming months.
The centrifuges could pave the way for work to create enough fissile material for a nuclear warhead.
Iran has repeatedly denied that it plans to develop nuclear weapons.
Two "cascades" of 164 centrifuges each have been installed at Natanz, the diplomats said on condition of anonymity.
Centrifuges spin uranium gas to enrich it to low levels for fuel and much higher levels for nuclear weapons.
Iran has said it eventually plans to install 54,000 centrifuges at Natanz.
Former UN nuclear inspector David Albright, whose Washington-based Institute for Science and International Security tracks Iran's nuclear activities, said Iran should be able to reach its goal of 3,000 centrifuges by the end of the year.
The International Institute for Strategic Studies in London (IISS) has said that once Iran has 3,000 centrifuges operating smoothly, it could produce enough highly enriched uranium for one bomb in nine to 11 months.
On Saturday, a group of ambassadors from non-aligned countries was taken on a tour of a nuclear facility near the city of Isfahan on what was billed as a transparency visit.
It was the first such trip since the UN imposed limited sanctions on Iran in December for refusing to suspend its uranium enrichment programme.
