Iran has told the UN nuclear watchdog that it has a second uranium enrichment plant under construction which will produce nuclear fuel only for the purpose of making electricity, the agency said on Friday.
"The agency also understands from Iran that no nuclear material has been introduced into the facility," International Atomic Enmergy Agency spokesman Marc Vidricaire said, adding that a letter from Iran had arrived on Monday.
"In response the IAEA has requested to Iran to provide specific information and access to the facility as soon as possible," he said, so UN inspectors could verify it would be used for peaceful purposes only.
Iran is under three sets of UN Security Council sanctions for refusing to freeze enrichment. Government officials said that Iran revealed the existence of a second enrichment plant in a letter sent Monday to International Atomic Energy Agency chief Mohamed ElBaradei.
It had previously said it was operating only one plant, which is being monitored by the IAEA.
A senior diplomat close to the IAEA said the Iran had told the agency the facility was a pilot, or experimental-level, enrichment site that was not yet in operation.
The Islamic Republic insists that it has the right to the activity to generate fuel for what it says will be a nationwide chain of nuclear reactors.
But because enrichment can make both nuclear fuel and weapons-grade uranium, the international community fears Tehran will use the technology to generate the fissile material used on the tip of nuclear warheads.
The revelation further burdens the chances of progress in scheduled October 1 talks between Iran and six world powers.
At that planned meeting – the first in more than a year – the five permanent UN Security Council members and Germany will be pressing Iran to scale back on its enrichment activities. But Tehran has declared that it will not bargain on enrichment.
Obama preparing announcement
A Western diplomat said US President Barack Obama was aware of the development and would make an announcement at the G-20 summit of major industrialised nations in the US city of Pittsburgh later on Friday.
The New York Times said Washington had been tracking the secret project for years and Obama decided to go public after Iran learned in recent weeks that Western intelligence agencies had penetrated the secrecy veiling the site.
Obama, British Prime Minister Gordon Brown and French President Nicolas Sarkozy planned to call on Iran to let the IAEA inspect the site immediately, then Times reported from Pittsburgh.
"This second enrichment facility could be very significant since it could prove the key to approaching potential nuclear weapons capacity for Iran," said a European diplomat, who emphasized he had seen no details of the project yet.
"It's good that Iran is coming clean about it," he said, alluding to lingering suspicions - which lacked proof - that Iran harboured further undeclared nuclear facilities, "but this could prove disastrous for non-proliferation."
No details about location
The officials said that the letter contained no details about the location of the second facility, when it had started operations or the type and number of centrifuges it was running.
The government officials – one speaking from his European capital outside Vienna, the other a diplomat in Vienna from a country accredited to the IAEA – demanded anonymity Friday because their information was confidential. One said he had seen the letter. The other told the AP that he had been informed about it by a UN official who had seen it.
While Iran's mainstay P-1 centrifuge is a decades-old model based on Chinese technology, it has begun experimenting with state-of-the art prototypes that enrich more quickly and efficiently than its old model.
UN officials familiar with the IAEA's attempts to monitor and probe Iran's nuclear activities have previously told the AP that they suspected Iran might be running undeclared enrichment plants.
The existence of a secret Iranian enrichment program built on black market technology was revealed seven years ago. Since then the country has continued to expand the program with only a few interruptions as it works toward its aspirations of a 50,000-centrifuge enrichment facility at the southern city of Natanz.
The last IAEA report on Iran in August said Iran had set up more than 8,000 centrifuges to churn out enriched uranium at the cavernous underground Natanz facility, although the report said that only about 4,600 of those were fully active.
The Associated Press and Reuters contributed to this report