A source in Iran's Supreme National Security Council, quoted by the Mehr and ISNA news agencies, said the halt at a uranium conversion facility near Isfahan was not connected with next Thursday's meeting of the UN's International Atomic Energy Agency.

The source, who was not identified, said work at Isfahan would resume once the maintenance work was over. He did not specify when the maintenance would begin, except to say that it would be after next Thursday's meeting.

"The maintenance work should have taken place in recent weeks, but we decided to keep the plant in operation. The repairs were delayed until after the IAEA meeting to avoid any misinterpretation," the official said.

"The work will last for 15 days, and (conversion) work will resume immediately afterwards," he said.

Iran had agreed to freeze uranium enrichment-related work under a November 2004 deal with Britain, France and Germany.

But in August the clerical regime rejected an offer of trade and other incentives in exchange for a long-term suspension and resumed activities at the Isfahan plant.

Conversion is a precursor to enrichment, and involves transforming raw uranium into a gas that can in turn be fed into centrifuges for the enrichment process -- which remains suspended.

Iran says it only wants to enrich uranium to make reactor fuel, but the process can be diverted to make nuclear weapons.

The IAEA's board has twice called on Iran to return to a full freeze.

An IAEA resolution passed on September 24 also stated that Tehran was in "non-compliance" with the nuclear Non-Proliferation Treaty -- an automatic trigger for taking the matter to the Security Council.

The IAEA's 35-nation board of governors is to meet again on Thursday.

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