The UN's International Atomic Energy Agency (IAEA) has called on Tehran to immediately halt all activities related to uranium enrichment, a process that can make the explosive material for nuclear weapons.

"We are not aware they have produced UF6," uranium hexafluoride gas, the feedstock for making enriched uranium , a senior IAEA official said at the agency's headquarters in Vienna.

Iran said last week it was already converting large amounts of uranium into this gas despite an IAEA resolution adopted September 18 calling for an immediate freeze on all enrichment activities.

The IAEA set a November 25 deadline, when its board of governors will next meet, for a definitive review of Iran's nuclear program.

The United States claims Iran hiding a covert weapons development program, and wants the IAEA to bring Iran before the UN Security Council for possible sanctions.

The IAEA official said actual production of new UF6, beyond test amounts already made, could take two weeks from when the conversion process is begun.

The United States has condemned Iran for resuming conversion but the key to any strong reaction from the IAEA depends on Europe's three main states -- Britain, France and Germany -- which have advocated constructive engagement with Iran and struck an agreement in October 2003 with Tehran to suspend the enrichment of uranium as a confidence-building measure.

Diplomats said Britain was now ready to urge the IAEA to bring Iran before the UN Security Council for possible sanctions if Iran defied the IAEA call for full suspension of uranium enrichment activities.

"For the Brits, actually producing UF6 is the cut-off point. Then they would be firm to take them to the Security Council," a senior European diplomat said.

Another European diplomat said however it was too soon to judge Iran, especially since suspending enrichment is not banned by the NPT, and the Iranians were not actually enriching uranium.

"We're waiting for the Iranian response. We're waiting to see what will actually be their reaction," the diplomat said.

Iran appealed Sunday for a negotiated settlement to its standoff with the IAEA but showed no inclination to abide by the agency's resolution

Foreign ministry spokesman Hamid Reza Asefi said in Tehran that since the IAEA resolution was passed, "Iran has not resumed enrichment but continues" to produce centrifuge parts and convert uranium.

Iran asserts it is merely trying to generate electricity and be self-reliant when it comes to nuclear fuel.

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