CHRONOLOGY: Iran's nuclear program

(Reuters) - Chief nuclear negotiator Ali Larijani, Iran's main contact with the West over Tehran's atomic program, has resigned, the government said on Saturday.

Here are the main events since it first emerged that Iran was carrying out sensitive work that it could use to make atomic bombs, although Tehran insists its activities are peaceful:

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

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

June 2003 - International Atomic Energy Agency (IAEA) report, after February inspection of Natanz and Arak, says Iran has failed to comply with nuclear Non-Proliferation Treaty.

October 2003 - Iran tells European Union negotiators France, Britain and Germany it will suspend all enrichment activities.

December 2003 - Iran signs protocol allowing snap inspections of nuclear facilities.

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. The European Union ends two years of talks in August after Iran said it would resume that work.

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 2-1/2-year suspension.

March 8 - IAEA report to Security Council says it cannot verify Iran's atomic activities are peaceful.

April 11 - Iran announces it has produced low-grade enriched uranium suitable for use in power stations; IAEA confirms.

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

July 31 - The U.N. Security Council demands that Iran suspend its nuclear activities by August 31.