President Barack Obama, accompanied by French President Nicolas Sarkozy, left, and British Prime Min
Enlarge Carolyn Kaster/AP

Sarkozy, Obama & Brown (left to right).

President Barack Obama, accompanied by French President Nicolas Sarkozy, left, and British Prime Min
Carolyn Kaster/AP

Sarkozy, Obama & Brown (left to right).

Saying that Iran "is refusing to live up to its international responsibilities," President Barack Obama just called on the International Atomic Energy Agency to immediately investigate what that country is doing at a second nuclear enrichment site it is constructing and had kept hidden for years.

The president has been joined by British Prime Minister Gordon Brown and French President Nicolas Sarkozy as he makes the announcement in Pittsburgh, where leaders of the G-20 nations have gathered for an economic summit.

Update at 9:03 a.m. ET. Here's the full audio of the president's statement:

Update at 8:51 a.m. ET. Tough talk from the leaders:

Obama also said Iran has "presented a direct challenge" to the world's efforts to present the spread of nuclear weapons. "The size and the configuration of this facility is inconsistent with a peaceful (nuclear) program," Obama said. "Iran is breaking rules that all nations must follow."

Sarkozy said that "if by December there is not an in-depth change by the Iranian leaders, sanctions will have to be taken."

Brown said "the level of deception by the Iranian government ... will shock and anger the whole international community." The U.S., U.K. and France have "no choice but to draw a line in the sand," he added.

Iran, the permanent members of the U.N. Security Council and Germany are due to meet Oct. 1 in talks about Iran's nuclear ambitions.