WASHINGTON – As Iran’s clerics review an offer from the great powers to rejoin nuclear disarmament talks, America and her allies have failed to reach full agreement themselves on the exact terms under which Iran would be considered to have suspended its enrichment of uranium.

In the meantime, America has proposed that in exchange for suspension – however it is finally decided – it will lift the trade embargo on Iran by providing nuclear technology for power generation and spare parts for its American-made civil aircraft.

An administration official and two Western diplomats confirmed yesterday that there is no shared definition between America, Britain, France, Germany, Russia, and the International Atomic Energy Agency on what would constitute suspension, the precondition under which America is prepared to join the European talks with Iran that were broken off earlier this year.

The White House is pressing for suspension to include the end of conversion of uranium yellowcake into the UF6 gas suitable for centrifuges to create nuclear fuel.

Meanwhile, Russia and the U.N. atomic watchdog have taken the view that Iran should be allowed to enrich uranium on a “research” level while negotiating the terms of a final agreement.

The only requirement all parties agree on, according to these sources, is that none of the UF6 gas derived from the yellowcake should enter the centrifuges on a large scale while Iran participates in talks.

The squabbling over the definition of suspension in the context of the Iran talks punctures the image Secretary of State Rice has tried to cultivate, that Iran faced the choice of suspension or international isolation, and that the offer of America to join talks created a unified international front against Iran.The demand that Iran suspend the conversion of yellowcake uranium to UF6 gas was the basis of the 2003 Paris agreement between Iran and France, Germany, and the United Kingdom.

However, proposals floated in February by Moscow would allow Iran to continue conversion and some “research enrichment.” In March Iran announced it had successfully enriched the UF6 gas to levels suitable for nuclear fuel, material suitable for both power and nuclear weapons.

Meanwhile, the perception that America has not abandoned its tough line on Iran is further weakened by yesterday’s New York Times story that Washington is offering a series of trade incentives to Iran – including the provision of nuclear power technology and spare parts for the country’s aging fleet of Boeing airliners – in exchange for only stopping the spinning of its centrifuges.

“The diplomacy, I would say, is at a sensitive stage,” the State Department spokesman, Sean McCormack, said yesterday. “This package has been presented to the Iranian Government and we want to give them a little bit of space to consider what’s in the package, both on the positive as well as the negative side.”

An administration official who requested anonymity said yesterday, “The offer was at first intentionally vague. The questions of suspension and also the time line for any future talks remain unknowns.”

Despite an early rebuke from Iran’s president last week, who dismissed the American offer as “propaganda,” recent signals from Tehran suggest that some negotiations may be possible. Mr. McCormack yesterday stressed that the European mission to Tehran that presented the package of incentives and disincentives to Iran found the discussions yesterday “very useful and constructive.”

Some nonproliferation experts are already raising alarms about the diplomatic path America is taking with Iran. “In the past there has been a clear notion of what suspension meant. And the IAEA was on the ground looking at things … they were on the ground with seals,” the director of the Washington based Wisconsin Project on Nuclear Arms Control, Gary Milhollin, said yesterday.

He added that he was troubled by any agreement with Iran that would allow “research enrichment.” Mr. Milhollin said, “We would need to have them put everything under seal and not do any research, conversion, or enrichment and not do any procurement.”

The executive director of the Nonproliferation Policy Education Center, Henry Sokolski, said research activities should be prohibited because of a risk it could provide cover for other secret nuclear programs.”Allowing them to do a little activity assumes you know everything about what they are doing and you can control everything,” he said. “But we know from experience we have never had that kind of knowledge or control with countries that want to hide something from us.”

An Iran expert at the American Enterprise Institute and former Pentagon analyst on Iran and Iraq, Michael Rubin, yesterday said the entire diplomatic offer to Iran was a serious mistake and a “capitulation.” “The devil is in the details, and the Iranians always parse the offer,” he said. “What the Bush administration is doing is deceiving the American public and not Iran.”

The board of governors of the International Atomic Energy Agency will meet Monday in Vienna.