Updated

A senior US official says the disclosure of a second, secret Iranian uranium enrichment facility "sets back Iran's nuclear program and increases our leverage. And we intend to use it." Several officials briefed reporters after President Obama, French President Sarkozy and British Prime Minister Gordon Brown revealed the existence of the facility, before the start of economic meetings at the G-20 summit in Pittsburgh.

President Obama called the plant, which is not yet operational, "a direct challenge" to the international community. President Sarkozy said "If by December there is not an in-depth change by the Iranian leaders, sanctions will have to be taken." Prime Minister Brown said the world "has no choice but to draw a line in the sand."

Officials say the US, British and French intelligence agencies put together a detailed briefing about the facility for the International Atomic Energy Agency, after Iran found out the plant's secrecy had been compromised. The officials say the US "has been aware of the facility for several years." It is an underground facility located in Qom, about 100 miles from Teheran. Officials say the plant is designed to house about three thousand centrifuges, not enough to enrich uranium for power generating purposes but just the right size "if you want to produce a bomb or two a year."

Aides say President Obama told Russian President Medvedev and Chinese President Hu Jintao about the plant earlier this week, in separate meetings in New York. US intelligence officials briefed counterparts from both countries. Officials suggest both leaders were trending toward accepting tighter sanctions on Iran and "are just now absorbing the latest revelation." Iranian President Ahmadinejad canceled plans for a news conference late today.

US officials intend to make the Qom plant a major topic when they joins talks on Iran's nuclear program for the first time next week. The permanent five members of the UN Security Council and Germany will meet with Iranian officials in Geneva. An officials says "Iran will be pressed to cooperate with the IAEA's investigation." Officials believe Iran will have to open the Qom plant to IAEA inspection, like they did with their uranium enrichment facility in Natanz after it was discovered. That will make it more difficult to divert enriched uranium to weapons use.
            The UN Security Council has imposed three sets of sanctions on Iran, since that country refused to end its uranium enrichment in December, 2006. The resolutions ban the sale of nuclear, military and high tech equipment to Iran. In addition, the US and European Union have frozen Iranian assets and the US has banned substantial trade with Iran since the 1979 takeover of the US embassy in Teheran. Despite the sanctions Iran has been able to continue to develop both its nuclear program and its development of ballistic missiles.