A senior official says the U.N nuclear agency believes Iran plans to start enriching uranium at a previously secret facility in 2011, AP reported.
The official says the International Atomic Energy Agency also believes that the site near the holy city of Qom will be able to house 3,000 uranium-enriching centrifuges.
A senior international official familiar with a new IAEA report said Monday that number could allow Iran to enrich enough material to be able to arm one nuclear warhead a year. He spoke on condition of anonymity because of the restricted nature of the information.
Iran denies it wants a nuclear weapons program, saying it is enriching only to create nuclear fuel.
President Barack Obama turned up the pressure Sunday by saying Iran is running out of time to agree a U.N.-brokered plan to ship its low-enriched enriched uranium out of the country to enrich it to a higher level. The West had hoped this plan would dramatically reduce its stockpile of enriched uranium and thwart any attempts to build nuclear weapons.
Iran's president warned the West not to pressure Tehran over its nuclear program, saying this only makes the country more determined to gain power by advancing its nuclear technology.
The comment by Mahmoud Ahmadinejad appeared to be a veiled threat that Iran would try to intensify its efforts to enrich uranium if nuclear negotiations with the international community fail.
"Cooperation with Iran in the nuclear field is in the interests of Westerners. Their opposition will make Iran more powerful and advanced," Ahmadinejad said in a statement posted late Sunday on the presidential Web site.
Iran sees its nuclear program as a matter of national pride and regional influence.