Iran is demanding that it be allowed to make an exception in its commitment to freeze all uranium enrichment (search) activities so it can operate about about two dozen centrifuges, diplomats said Wednesday.

The Iranians have told the International Atomic Energy Agency (search) — the U.N. nuclear watchdog — that they want to operate the centrifuges "for research purposes," the diplomats told The Associated Press.

They have asked the IAEA to exempt around 24 of the devices from the agency seals meant to ensure the enrichment program is completely at a standstill, one of the diplomats said.

The IAEA had no immediate comment. But another diplomat who is familiar with the agency said it was resisting the demand for an exemption.

The move comes on the eve of an IAEA board meeting that will examine Iran's compliance to international demands meant to reduce suspicions about its nuclear activities. Among them are call for a suspension of all enrichment and related activities — something Iran agreed to earlier this month in a deal with European negotiators.

Iran said Monday it froze all uranium enrichment programs, weakening a U.S. effort to refer Tehran's suspect nuclear activities to the U.N. Security Council.

The suspension was clearly timed to coincide with the start of the 35-nation IAEA board meeting and met a key demand of the last board meeting in September. It thus deprived the Americans of arguing that Tehran was defying the U.N. agency.

Still, Iran has said suspension will be only temporary and insists that it has the ultimate right to enrich uranium. It dismisses U.S. assertions that it wants to use the technology to make weapons, saying it is interested only in generating nuclear power.

And Tehran's announcement of a start to suspension came only after it had already converted a few tons of raw uranium into the gas used as feedstock for enrichment by centrifuges. While not prohibited from doing so until Monday — when the freeze took effect — conversion continued until shortly before the deadline, raising doubts about Iran's interest in dispelling international concerns.

One of the diplomats — an EU delegate to the upcoming IAEA board meeting who spoke on condition of anonymity — said the new Iranian demand on centrifuge operation dealt a further blow to initial European optimism about the deal, reached earlier this month in Paris.

Tehran ultimately plans to run 50,000 centrifuges to enrich uranium in the central city of Natanz. Iran says the Natanz facility is meant to meet the fuel requirements of a nuclear reactor being built with Russian help that is expected to be finished next year.

For now, it is far short of that goal, possessing less than 1,000 centrifuges, most of them bought secretly through the black market network of Pakistani scientist Abdul Qadeer Kahn, the rest made domestically.

But experts estimate Iran is not far away from being able to run the 1,500 centrifuges that are needed for making the amount of highly enriched uranium — about 45 pounds — needed for one crude weapon a year.

IAEA head Mohamed ElBaradei said earlier this week he expected to have a definitive ruling by Thursday — the opening of the board meeting — on whether Iran had honored its pledge to stop all activities covered by the freeze.

A confidential draft resolution on Iran made available to The Associated Press and being revised for approval by the board requests that ElBaradei monitor the implementation of the suspension and "report immediately to the board" if the freeze is not implemented.

While not prohibited from enrichment under the Nuclear Nonproliferation Treaty, Iran has been under intense pressure to agree to at least a freeze — if not to scrap its program — as a way of reducing international suspicions.

ElBaradei, the U.N. agency head, said Monday he believed the Iranians processed about two tons of raw uranium into the gas in the period leading up to Monday's suspension deadline.

A diplomat with nuclear expertise said that amount would be about a quarter of the quantity needed to produce the 25 kilograms — or more than 50 pounds — of weapons-grade uranium for one small nuclear weapon.