TIMELINE: Iran's nuclear program

(Reuters) - Iranian President Mahmoud Ahmadinejad said on Tuesday Iran has started to install 6,000 advanced centrifuges at its Natanz uranium enrichment facility.

Here is a chronology of events since it emerged that Iran was carrying out sensitive work that it could use to make atomic bombs. Iran says its nuclear program is for peaceful energy generation.

August 2002 - The exiled opposition National Council of Resistance of Iran reports the existence of a uranium enrichment facility at Natanz and a heavy water plant at Arak.

December 2002 - The United States accuses Iran of "across-the-board pursuit of weapons of mass destruction".

June 2003 - An IAEA report, after February inspection of Natanz and Arak, says Iran has failed to comply with nuclear Non-Proliferation Treaty.

November 2004 - Iran promises EU negotiators it will suspend all nuclear fuel processing and reprocessing work.

September 2, 2005 - IAEA report confirms Iran has resumed uranium conversion at Isfahan.

January 10, 2006 - Iran removes U.N. seals at Natanz enrichment plant and resumes nuclear fuel research.

February 4 - IAEA votes to report Iran to the U.N. Security Council. Iran ends snap U.N. nuclear inspections the next day.

February 14 - Iran restarts small-scale feeding of uranium gas into centrifuges at Natanz after two-and-a-half year suspension.

April 11 - Ahmadinejad declares that Iran had produced its first batch of enriched uranium. World powers condemn Iran for advancing its program in defiance of the United Nations.

June 5 - EU foreign policy chief Javier Solana delivers a package of incentives from world powers if Iran agrees to halt uranium enrichment.

August 31 - IAEA announces Iran has not met a deadline to suspend its atomic fuel program.

December 23 - Security Council votes for sanctions and gives 60 days to suspend enrichment. Iran calls the resolution illegal.

March 24, 2007 - The Security Council unanimously approves further arms and financial sanctions against Iran.

April 18 - 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.