World powers are prepared to compromise on a long-standing demand that Iran commit to a prolonged moratorium on uranium enrichment and now are asking only for suspension during talks on Tehran's nuclear program, diplomats and officials said Wednesday.

That proposal — and a connected offer to allow Iran to continue with uranium conversion, which is linked to enrichment — was the latest in a series of concessions meant to entice Iran into starting talks and to defuse the possibility of U.N. sanctions if it remains defiant.

Such changes to the previous stance on enrichment signal a possible readiness by the United States and key allies to accept some limited form of the activity, despite years of warnings from Washington that Tehran was seeking the technology to make nuclear arms.

CountryWatch: Iran

Since talks between key European nations and Iran broke off in August, the public stance by the European negotiators and the United States has been that Iran must commit to a long-term moratorium as a precondition for talks.

Still, one of the diplomats said that — despite the concession — a long-term moratorium remained the preferred goal of the six nations that approved the package last week in Vienna.

EU foreign policy chief Javier Solana — who formally presented the offer to Iranian officials this week — said Wednesday that the issue of enrichment would have to be reassessed once talks were completed.

"In principle ... they will have to stop now, we will have to negotiate with no process of enrichment in place," he told reporters in the German city of Potsdam. "After the finalization of the negotiations we will see what happens."

Solana said the incentive offer came with "no specific timeframe," but that he expected an Iranian answer within "weeks."

He said nothing about conversion. But diplomats told The Associated Press on condition of anonymity that Iran would be allowed to continue with that activity — a precursor to enrichment — under terms offered Tehran in an attempt to bring it to the negotiating table. Previously, Washington and its allies also had called for a freeze on conversion.

In Washington, U.S. 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. sanctions if it rejects the incentives. But Russian Foreign Minister Sergei Lavrov said Moscow would support sanctions only if Iran violates the Nuclear Nonproliferation Treaty — a possible indication of continued discord among the six powers endorsing the Iran package of rewards.

Diplomats had said that both Russia and China agreed to possible sanctions during the Vienna talks on the package if Iran rejected the initiative.

Diplomats have told AP that Germany — which participated in drawing up a six-nation package of perks and punishments meant to persuade Iran to stop enriching uranium — has been advocating that Tehran be allowed some small-scale activity.

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

Iran announced 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 an internationally supervised program on such 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 later, but also has 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 — fuel-grade uranium, as opposed to weapons-grade enriched to levels above 90 percent — appeared to be true.

The report also said uranium conversion "is still ongoing," adding that more than 110 metric tons (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, experts say.

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

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

It has not been made public but some of its contents have been leaked, revealing major concessions by the U.S. meant to entice Iran to the negotiating table — among them an offer to join key European nations in providing some nuclear technology to Tehran if it stops enriching uranium, diplomats say.

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

A diplomat said Wednesday that Iran also was being offered a chance to replenish its aging civilian fleet with new aircraft — as well as with Boeing parts — because the package of incentives includes the prospect of lifting an embargo on such products.

Washington has broken with decades of official policy of no high-level diplomatic contacts with Tehran, announcing last week that it was ready to join talks with the Islamic republic over its nuclear program.