"IAEA Director General Yukiya Amano noted with concern this decision, as it may affect, in particular, ongoing international efforts to ensure the availability of nuclear fuel for the Tehran Research Reactor," said Gill Tudor, spokeswoman for the Vienna-based International Atomic Energy Agency.

"The Director General reiterated the Agency's readiness to play an intermediary role on the issue of the Tehran Research Reactor," she added.

Iran's hardline President Mahmoud Ahmadinejad prompted sharp reactions from world powers after he called on his country's atomic chief Sunday to begin producing 20-percent enriched uranium.

The Islamic republic needs the fuel for a research reactor in Tehran that makes radioisotopes for medical purposes such as cancer treatment.

But Iran has so far seemed reluctant to enter a UN-brokered deal, which would require it to ship its low-enriched uranium (LEU) to Russia for further processing.

Western countries insist Iran do so to prove that its controversial nuclear drive is entirely peaceful as Tehran claims, but Iran sees such a deal as a ruse by the West to confiscate its stockpiled uranium.

The IAEA confirmed that it had "received a letter from the Atomic Energy Organization of Iran (AEOI) on 8 February 2010."

"The AEOI informed the Agency that production of less than 20-percent enriched uranium is being foreseen at the Pilot Fuel Enrichment Plant at Natanz for fuel for the Tehran Research Reactor," it said.

Tehran's envoy to the UN nuclear watchdog, Ali Asghar Soltanieh, told AFP on Monday that in the letter: "I invited the agency's inspectors to be present during this whole process because we always put all activities, including enrichment, under IAEA supervision and surveillance and control."

Asked when Iran's enrichment plant in Natanz would be ready to actually start enriching to higher levels, Soltanieh said preparations would begin on Tuesday.

But he acknowledged it may be a while before the 20-percent enriched uranium would actually start being produced.

"It takes time but we'll do it," Soltanieh said.

All rights reserved. © 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.