The United States criticized Iran on Tuesday for its continued violation of UN resolution on disputed nuclear program while expressing its doubt about Iran's claim that it had started work to install 6,000 new centrifuges to enrich uranium.
"I can't substantiate the claims. There are always multiple claims coming out of Iran about progress on this, progress on that. I don't think the underlying situation has changed," Secretary of State Condoleezza Rice told reporters.
U.S. National Security Council spokesman Gordon Johndroe also said Iran's latest claim about its nuclear development could not be verified. But he said it was not surprising to hear the news.
Johndroe warned that Iran will face new international isolation and sanctions after refusing to comply with UN Security Council resolutions that demand the halt of uranium enrichment.
Rice and Johndroe made the remarks hours after Iranian President Mahmoud Ahmadinejad said Iran has begun installing 6,000new centrifuges at its uranium enrichment plant.
Prior to its latest nuclear development, Iran has already installed around 3,000 centrifuges at an underground enrichment facility at Natanz, in central Iran, according to a statement by Ahmadinejad in November 2007.
The United States and its Western allies fear that Tehran is trying to build nuclear weapons. Iran insists that its nuclear program is for peaceful purposes only.
The UN Security Council has imposed three sanctions against Tehran's nuclear program since December 2006.