The United Nations nuclear agency said Iran has begun installing advanced centrifuges at its main uranium enrichment site.
The report by the International Atomic Energy Agency said Iran has started installing the new IR-2m centrifuges at its Natanz plant south of Tehran. The IAEA believes at least 100 of these centrifuges have been mounted inside the plant.
If operated successfully, the advanced centrifuges could speed the enrichment of uranium to a level the West fears could be used to produce an atomic weapon.
The United States warned Iran Thursday that it will face further pressure and isolation, if it fails to address international concerns about its nuclear program during talks with six world powers (the U.S., Britain, China, France, Russia and Germany) on February 26, in Kazakhstan. White House spokesman Jay Carney said the window for diplomacy with Iran remains open but, as he put it, "that window will not remain open indefinitely."
Previous international efforts to address concerns about Iran's nuclear program have made little progress, with Iran maintaining its nuclear program has peaceful aims.
Some information for this report was provided by AFP and Reuters.