The International Atomic Energy Agency (IAEA) on Wednesday gave the final go-ahead for the removal of seals it put on the uranium conversion facility on the outskirts of Isfahan when Iran suspended sensitive nuclear activities in November.
Iran sparked international concern when it ended the nine-month suspension of uranium conversion on Monday, but up until the cutting of the metal seals on key machinery the resumption has only been partial.
"We have started," Iran's atomic energy agency vice-president Mohammad Saidi said. "It is happening under the supervision of the agency."
Throughout the escalation of tensions, Iran has been at pains to emphasise it was resuming conversion activities in concert with the IAEA, whose inspectors have installed surveillance equipment to monitor the process.
While it was Iranian workers who removed the seals, the process has taken place under IAEA supervision.
Mindful of playing by international rules, Iran waited for the agency to finish installing surveillance equipment before breaking the seals.
The IAEA said it will confirm the
removal of the seals
"The seals are in the process of being cut. Once the removal of the seals is completed we will confirm this to the (IAEA) board," IAEA spokeswoman Melissa Fleming said in Vienna.
The IAEA "told us in a letter that there was no obstacle and that (the agency) authorises us to remove the seals, which will be returned to them afterwards," said Saidi.
The move comes as the European Union tries to win approval at an emergency IAEA meeting in Vienna for a draft resolution calling on Iran to reverse its decision to push ahead with the nuclear fuel work.
Indicating the difficulties of forging an agreement, a planned formal IAEA meeting on Wednesday was cancelled because diplomats remained in closed-door talks on the EU resolution.
Conversion turns uranium ore, or yellowcake, into a feed gas for making enriched uranium, which can be the fuel for reactors or the explosive core of atomic bombs.
Iran had suspended uranium conversion and enrichment as a goodwill gesture during nine months of talks with the European Union intended at staving off UN Security Council intervention.
The prospect of the talks succeeding has been dealt a severe blow by Iran's resumption of conversion.
Iran emphasises that its right to the nuclear fuel cycle is legally enshrined under the nuclear Non-Proliferation Treaty and it has infringed no international rules by resuming the activities.
The United States accuses Tehran of seeking to manufacture a nuclear weapon, a charge denied by Iran, but Washington points to Iran's past failure to transparently report nuclear activities as grounds for suspicion.
Insult to Iranians
New President Mahmoud Ahmadinejad has described the offer of nuclear, commercial and political cooperation made on Friday by the Europeans in exchange for Iran renouncing the activities as an "insult to the Iranian people".
"The Europeans talk as though the Iranian people were a backward people, as if they were still in the last century when they dominated our country," he seethed.
"The Europeans talk as though the Iranian people were a backward people, as if they were still in the last century when they dominated our country"
Mahmood Ahmadinejad, president of Iran
But while Ahmadinejad's comments published on Tuesday appeared to confirm Western fears he will adopt a tough line on the nuclear issue, he emphasised he was leaving the door open for more talks with the Europeans.
Ahmadinejad has yet to appoint a new government, but one of the candidates for the post of foreign minister - parliamentary foreign affairs committee head Aleaddine Boroujerdi - made it clear that there was no going back on the move.
The best guarantee that Iran's nuclear programme is peaceful was the "infallible watching of the IAEA cameras," he said. "I hope that the Europeans will also accept this reality."
He added that the government still had not made any decision on restarting Iran's uranium enrichment plant in the city of Natanz.
Enrichment remains suspended, but officials emphasise this is only temporary.