"About 12 o'clock today, we delivered a letter officially announcing to the agency that we are going to start activities for the enrichment up to 20 percent in order to produce the fuel required for the Tehran research reactor," Ali Asghar Soltanieh said.

"And in the same 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."

Iran's atomic chief Ali Akbar Salehi had announced late Sunday that Tehran would begin enriching uranium to 20 percent from Tuesday and that the IAEA would be informed of its decision before then.

The announcement drew a sharp riposte Monday from world powers, who fear that Iran's nuclear enrichment programme is masking an attempt to make atomic weapons.

French Foreign Minister Bernard Kouchner insisted that Iran does not have the capacity to enrich uranium to 20 percent and accused Tehran of "blackmail."

The Iranians "do not know how to make fuel" for their existing medical reactor, he told reporters at a meeting in Paris.

But Soltanieh was adamant that Iran would be able to enrich its stockpile of low-enriched uranium (LEU) still further.

"I'm sorry to say that (France's) knowledge is incorrect," he told AFP.

"We do have the capability of going to 20 percent. And we have the capability to work on the fuel fabrication," he said, dismissing suggestions that Iran would not be able to turn the 20-percent enriched fuel into fuel rods.

Only a few years ago, the international community had said Iran would never be able to enrich, "but we have been able to do it," Soltanieh said.

"Then they said we wouldn't be able to go to the next stage, in the cascade arrangement of the machines. We were able. Then they said, we could not go to industrial production, but we were able."

The envoy said Iran had decided to enrich on its own, because the West had so far not responded to its own suggestions for a managed fuel swap.

"It's about eight months that we are waiting since the letter of June 2, 2009 that I wrote to the IAEA's former director general Mohamed ElBaradei, and more than four months passed since our negotiations with France, US and Russia and IAEA in Vienna," he complained.

But there had been no response so far.

"Therefore we had to choose other options and namely to produce it ourselves for our research reactor which is producing radioistopes for hospitals."

Asked when Iran's enrichment plant in Natanz would be ready to actually start enriching to higher levels, the envoy 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.

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