Iranian President Mahmoud Ahmadinejad will inaugurate the country's first nuclear fuel production complex later on Thursday, an Iranian official told Reuters.
Iran said earlier it would review an offer of talks on its nuclear program from the United States and five other world powers.
Details of Iran's nuclear program first emerged in August 2002 when the exiled opposition National Council of Resistance of Iran reported the existence of a uranium enrichment facility at Natanz and a heavy water plant at Arak. Here is a timeline of Iran and its nuclear program in the last two years.
April 18, 2007 - IAEA says Iran has started up more than 1,300 centrifuge machines in an accelerating campaign to lay a basis for industrial scale enrichment in the Natanz complex.
November 2 - Six powers -- Britain, France, Germany, the United States, Russia and China -- agree to push ahead with more sanctions.
December 3 - A U.S. National Intelligence Estimate says Iran put its bid to build a nuclear bomb on hold in 2003 and it remains on hold. Two days later Ahmadinejad declares victory over the United States and IAEA head Mohamed ElBaradei says Iran has been somewhat vindicated.
December 11 - The opposition NCRI says Iran did shut down its program in 2003 but restarted it a year later. The group says recent U.S. analysis gives the wrong impression.
January 11-12, 2008 - ElBaradei makes a rare visit to Tehran to push for swifter cooperation in wrapping up the IAEA inquiry.
March 3 - U.N. Security Council adopts a third sanctions resolution targeted at Iran's nuclear program.
July 19 - Iranian officials rule out any freeze in uranium enrichment during talks in Geneva on the program, attended for the first time by a senior U.S. diplomat.
August 2 - An informal deadline lapses for Iran to respond to an offer from the United States, Britain, France, Germany, China and Russia for talks on its disputed nuclear program.
August 5 - Iran delivers a letter to world powers but gives no concrete reply to a demand to freeze its nuclear activity, a defiant step the U.S. says amounts to obfuscation. The next day the U.S. and Britain say major powers agreed to consider more U.N. sanctions.
September 15 - The IAEA says Iran has blocked a U.N. inquiry into whether it researched ways to make a nuclear bomb as Britain said it would push hard for tougher sanctions.
November 26 -Iran says it is now running 5,000 uranium enrichment centrifuges, signaling an expansion of work the West fears is aimed at making nuclear weapons.
-- This is higher than the 3,800 such machines the IAEA cited in a November 19 report, which was based on a visit by its inspectors to Iran's Natanz enrichment plant on November 7.
February 5, 2009 - Russia says it plans to start up a nuclear reactor at the Bushehr plant by the end of 2009.
February 19 - A new IAEA report shows a significant increase in Iran's reported stockpile of low-enriched uranium since November to 1,010 kg, enough, some physicists say, for possible conversion into high-enriched uranium for one bomb.
February 25 - Iran denies it has slowed down its nuclear activities and says it plans to install 50,000 centrifuges to enrich uranium over the next five years.
March 20 - New U.S. President Barack Obama calls for engagement that is honest and grounded in mutual respect. Iran cautiously welcomes the overture, saying it wanted to see practical steps.
April 8 - The U.S. takes another tentative step toward better ties with Iran to become a full participant in nuclear talks with Tehran, but it shows no sign of a detente.
April 9 - Iran says Ahmadinejad will inaugurate the country's first nuclear fuel production complex.