Yesterday in Vienna, the United States, France, and England "presented detailed evidence" to the International Atomic Energy Agency demonstrating that Iran has a covert uranium enrichment facility near the city of Qum, President Obama announced at the G-20 economic summit in Pittsburgh this morning.

The decision to build this facility represents "a direct challenge to the basic compact at the center of the nonproliferation regime," Obama said, appearing with President Nicolas Sarkozy of France and Prime Minister Gordon Brown of England.

"We expect the IAEA to immediately investigate this disturbing information," he said.

However Obama added: "We have offered Iran a clear path toward greater international integration if it stands up to its obligations, and that offer stands."

Senior administration officials told news organizations before Obama's remarks that Iran has a "secret underground plant to manufacture nuclear fuel," 100 miles southwest of Tehran. The enrichment plant, however, is said not to be in operation.

President Obama said today "the size and configuration of this facility is inconsistent with a peaceful program."

He said there is now a "sense of urgency" about an October 1 meeting in Geneva with Iran, Germany, and the permanent members of the Security Council (the so-called P5+1).

Iran sent the IAEA a letter earlier this week revealing that a "new pilot fuel-enrichment plant is under construction."

The Obama Administration made the decision to go public with the evidence about the plant, which the US has reportedly been tracking for years, because Iran learned that Western countries knew about the facility, the New York Times reports.

The IAEA, for its part, has asked Iran for specific information about the facility, and access to it, as soon as possible.

Iranian President Mahmoud Ahmadinejad told the Washington Post in an interview this week that the country's nuclear program has energy and medical aims, and he said he would buy enriched uranium for the U.S. for medical purposes.

Late Update: Here's the video of Obama's remarks.

Late Late Update: Full Transcript of the remarks of the three leaders, provided by the White House.

8:43 A.M. EDT

PRESIDENT OBAMA: Good morning. We are here to announce that yesterday in Vienna, the United States, the United Kingdom, and France presented detailed evidence to the IAEA demonstrating that the Islamic Republic of Iran has been building a covert uranium enrichment facility near Qom for several years.

Earlier this week, the Iranian government presented a letter to the IAEA that made reference to a new enrichment facility, years after they had started its construction. The existence of this facility underscores Iran's continuing unwillingness to meet its obligations under U.N. Security Council resolutions and IAEA requirements. We expect the IAEA to immediately investigate this disturbing information, and to report to the IAEA Board of Governors.

Now, Iran's decision to build yet another nuclear facility without notifying the IAEA represents a direct challenge to the basic compact at the center of the non-proliferation regime. These rules are clear: All nations have the right to peaceful nuclear energy; those nations with nuclear weapons must move towards disarmament; those nations without nuclear weapons must forsake them. That compact has largely held for decades, keeping the world far safer and more secure. And that compact depends on all nations living up to their responsibilities.

This site deepens a growing concern that Iran is refusing to live up to those international responsibilities, including specifically revealing all nuclear-related activities. As the international community knows, this is not the first time that Iran has concealed information about its nuclear program. Iran has a right to peaceful nuclear power that meets the energy needs of its people. But the size and configuration of this facility is inconsistent with a peaceful program. Iran is breaking rules that all nations must follow -- endangering the global non-proliferation regime, denying its own people access to the opportunity they deserve, and threatening the stability and security of the region and the world.

It is time for Iran to act immediately to restore the confidence of the international community by fulfilling its international obligations. We remain committed to serious, meaningful engagement with Iran to address the nuclear issue through the P5-plus-1 negotiations. Through this dialogue, we are committed to demonstrating that international law is not an empty promise; that obligations must be kept; and that treaties will be enforced.

And that's why there's a sense of urgency about the upcoming meeting on October 1st between Iran, the permanent members of the U.N. Security Council, and Germany. At that meeting, Iran must be prepared to cooperate fully and comprehensively with the IAEA to take concrete steps to create confidence and transparency in its nuclear program and to demonstrate that it is committed to establishing its peaceful intentions through meaningful dialogue and concrete actions.

To put it simply: Iran must comply with U.N. Security Council resolutions and make clear it is willing to meet its responsibilities as a member of the community of nations. We have offered Iran a clear path toward greater international integration if it lives up to its obligations, and that offer stands. But the Iranian government must now demonstrate through deeds its peaceful intentions or be held accountable to international standards and international law.

I should point out that although the United Kingdom, France, and the United States made the presentation to Vienna, that Germany, a member of the P5-plus-1, and Chancellor Merkel in particular, who could not be here this morning, wished to associate herself with these remarks.

I would now like to turn to President Sarkozy of France for a brief statement.

PRESIDENT SARKOZY: (As translated.) Ladies and gentlemen, we have met yesterday for a meeting -- a summit meeting of the Security Council on disarmament and nuclear disarmament. I repeated my conviction that Iran was taking the international community on a dangerous path. I have recalled all the attempts that we have made to offer a negotiated solution to the Iranian leaders without any success, which what has been revealed today is exceptional. Following the enriching plant of Natanz in 2002, it is now the Qom one which is revealed. It was designed and built over the past several years in direct violation of resolutions from the Security Council and from the IAEA. I am expecting from the IAEA an exhaustive, strict, and rigorous investigation, as President Obama just said.

We were already in a very severe confidence crisis. We are now faced with a challenge, a challenge made to the entire international communities. The six will meet with the Iranian representatives in Geneva. Everything -- everything must be put on the table now.

We cannot let the Iranian leaders gain time while the motors are running. If by December there is not an in-depth change by the Iranian leaders, sanctions will have to be taken. This is for the peace and stability. Thank you.

PRIME MINISTER BROWN: America, the United Kingdom, and France are at one. Iran's nuclear program is the most urgent proliferation challenge that the world faces today.

As President Obama and President Sarkozy have just said, the level of deception by the Iranian government, and the scale of what we believe is the breach of international commitments, will shock and anger the whole international community, and it will harden our resolve.

Confronted by the serial deception of many years, the international community has no choice today but to draw a line in the sand. On October the 1st, Iran must now engage with the international community and join the international community as a partner. If it does not do so, it will be further isolated.

And I say on behalf of the United Kingdom today, we will not let this matter rest. And we are prepared to implement further and more stringent sanctions.

Let the message that goes out to the world be absolutely clear: that Iran must abandon any military ambitions for its nuclear program. Thank you.

END 8:51 A.M. EDT