IAEA: Iran acknowledges second nuclear facility

(CNN) - Iran has admitted the existence of a second uranium enrichment plant in a letter sent to the International Atomic Energy Agency, a spokesman for the nuclear watchdog agency said Friday.

"I can confirm that on 21 September, Iran informed the IAEA in a letter that a new pilot fuel enrichment plant is under construction in the country," said IAEA spokesman Marc Vidricaire.

He said the letter stated that Iran's enrichment level would be up to 5 percent. The IAEA has requested that Iran provide specific information and access to the nuclear facility as soon as possible.

Several diplomatic sources told CNN they were aware of the letter.

The second nuclear facility, located on a military base near the holy city of Qom, is thought to be capable of housing 3,000 centrifuges, not enough to produce nuclear fuel to power a reactor, but sufficient to manufacture bomb-making material, a U.S. diplomatic source who read the letter told CNN.

U.S. and French intelligence officials have known about the facility for several months, the source said. When Iran discovered that Western nations had knowledge of the facility, it sent the letter to the IAEA.

Iran claims its nuclear enrichment program is intended for peaceful purposes, but the international community accuses it of continuing to try to develop nuclear weapons capability. Until the new letter, it had acknowledged only a uranium enrichment plant in Natanz, which nuclear inspectors visited recently.

The United Nations Security Council has implemented sanctions against Iran for refusing to freeze enrichment.

White House sources said Friday that President Barack Obama will make an announcement regarding the second Iranian facility at a news conference Friday morning before the opening of the G-20 economic summit in Pittsburgh, Pennsylvania.

The New York Times reported that Obama, British Prime Minister Gordon Brown and French President Nicolas Sarkozy plan to accuse Iran of hiding its nuclear facilities from IAEA inspectors.

The three leaders are expected to demand that Iran allow the IAEA to conduct an immediate inspection of the facility in Qom, the New York Times said.

Iranian President Mahmoud Ahmadinijad did not mention the plant during his visit to New York this week for U.N. General Assembly sessions. He reiterated earlier claims that Iran has fully cooperated with nuclear inspectors.

Obama has already said that "serious sanctions" are a possibility if Iran fails to adequately address the nuclear issue.

Middle East analyst Meir Javendafar said it was "very significant" that Iran had come clean.

"When pressured the regime does show some sign of flexibility," said Javendafar, author of a book called "The Nuclear Sphinx of Tehran: Mahmoud Ahmadinejad and the State of Iran." He said ultimately, Iran is fearful of international isolation.

–CNN's Matthew Chance in Moscow, Reza Sayah in Islamabad, Kevin Flower in Jerusalem and John Roberts in New York contributed to this report.