He said nothing about uranium conversion, which is a step preceding enrichment. But diplomats told The Associated Press that Iran would be allowed to continue that activity. Previously, Washington and its allies wanted a freeze on conversion, too.

The diplomats spoke on condition of anonymity because they are not authorized to divulge the contents of the offer.

In Washington, State Department spokesman Sean McCormack said suspension was a precondition for the talks, adding: "Beyond that, I am not going to speculate. Beyond that, we are truly into the realm of the hypothetical and theoretical."

France warned Wednesday that Iran would face U.N. Security Council sanctions if it rejected the proposal for opening talks. But Russian Foreign Minister Sergei Lavrov said Moscow would support sanctions only if Iran violated the Nuclear Nonproliferation Treaty, a possible indication of continued discord among the six powers involved in the effort.

Diplomats said previously that both Russia and China agreed during last week's talks in Vienna to the possibility of imposing sanctions if Iran rejected the initiative.

Diplomats told the AP that Germany is been advocating that Tehran be allowed some small-scale enrichment.

Mohamed ElBaradei, the head of the Vienna-based International Atomic Energy Agency, backs that view, arguing that with Iran already successful in small-scale enrichment, it is unlikely to give up its right to such activity.

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

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

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

In an April report, ElBaradei said Iran seemed to be accurately claiming to have enriched small amounts of uranium to a level of 3.6 percent, rich enough for reactor fuel, but far below the 90 percent level needed for weapons-grade material.

The report also said uranium conversion "is still ongoing," adding that more than 120 tons had been converted over eight months.

A new report from ElBaradei will be circulated to the IAEA's 35-nation board Thursday, ahead of the U.N. watchdog agency's meeting next week. One diplomat said it was unlikely to have major revelations about Tehran's activities.

The Iran package was approved last week by the five permanent U.N. Security Council members and Germany.

It has not been made public but some of details have been leaked, revealing major U.S. concessions designed to entice Iran to the negotiating table - among them an offer for Europe to provide some nuclear technology to Tehran in exchange for giving up enrichment, diplomats say.

A European offer of light water reactors for civilian nuclear energy purposes was revealed last month.

A diplomat said Wednesday that Iran also was being offered a chance to acquire jetliners and get Boeing parts for its aging civilian planes, with the initiative holding out the prospect of lifting an embargo on such sales.