Iran's President: 'Smoking Gun' a U.S. Fabrication

Dec. 20, 2009— -- Iran's president is dismissing a newly revealed secret document that purportedly shows Iran has been trying to develop a crucial component of a nuclear bomb, calling it a fabrication concocted by the U.S. government.

In an exclusive interview with ABC News' Diane Sawyer, President Mahmoud Ahmadinejad refused to look at a copy of the document, waving it away.

"No, I don't want to see this kind of document. These are some fabricated papers issued by the American government," he said.

Watch Diane Sawyer's interview with Iranian President Mahmoud Ahmadinejad Monday night on "ABC World News with Diane Sawyer."

It was the first public comment by the Iranian leader on the two-page document since its existence was revealed by The Times of London last week.

According to the newspaper, the document shows Iran has been secretly working on testing a neutron initiator -- the part of a nuclear bomb that triggers an explosion. The technology has no use aside from detonating a nuclear weapon.

Critics of the Iranian regime have seized on the revelation as a smoking gun -- one of the strongest indicators yet of a continuing nuclear weapons program in Iran.

But when asked point-blank whether Iran had been testing a neutron initiator, the Iranian president was dismissive.

"I think that some of the claims about our nuclear issue have turned into a repetitive and tasteless joke," Ahmadinejad said in the interview.

Asked about Ahmadinejad's allegation that the U.S. government fabricated documents, White House Senior Adviser David Axelrod said: "Of course that's nonsense."