Iran announced on April 11 that it had enriched uranium for the first time, using 164 centrifuges. Still, the country would need tens of thousands of centrifuges to produce adequate fuel for a nuclear reactor or material for a warhead.

Those advocating that Iran be allowed to do research and development on enrichment say it is better to permit it an internationally supervised program on a small scale and try to gain agreement from Tehran that it will not develop a large industrial program.

Iran has said it intends to move toward large-scale enrichment involving 3,000 centrifuges by late 2006 and 54,000 centrifuges after that, but it has also indicated it might suspend large-scale enrichment to ease tensions.

In an April report, ElBaradei said Iran's claim to have enriched small amounts to a level of 3.6 percent appeared to be true. The level qualifies as fuel grade uranium, as opposed to weapons grade enriched to levels above 90 percent.

It also said uranium conversion -- an activity linked to enrichment -- "is still ongoing," adding that more than 120 tons have been converted over the past eight months. Were it used for weapons, that amount would be enough for more than 15 crude nuclear bombs, according to experts.

The Iran package was approved last week in Vienna by the United States, Russia, China, Britain and France -- the five permanent U.N. Security Council members -- plus Germany.

While it has not been made public, some of its contents have been leaked, revealing major concessions by the United States meant to entice Iran to the negotiating table. Those include an offer to join key European nations in providing some nuclear technology to Teheran if it stops enriching uranium, diplomats say.