Iran's President Mahmoud Ahmadinejad says evidence purporting to show Iran tried to build a nuclear trigger in 2007 is false.

Over the weekend, ABC's Diane Sawyer asked the hard-line leader of the Islamic Republic about the 'smoking gun,' an Iranian document recently cited in the Times of London.

"As far as your question is concerned, I think that some of the claims made by the Americans and other Western statesmen about our nuclear issue have turned into a repetitive and tasteless joke," Ahmadinejad said.

"They are fundamentally not true," he said.

The report comes on the heels of a revelation that Tehran has been operating secret centrifuges to process nuclear material.

Meanwhile, on Tuesday Ahmadinejad dismissed the Obama administration's year-end deadline to accept a United Nations deal to decrease its stockpile of enriched uranium.