(Reuters) - Below are key dates since it emerged that Iran was carrying out sensitive work that it could use to make atomic bombs. 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 - An IAEA report, after February inspection of Natanz and Arak, says Iran has failed to comply with nuclear Non-Proliferation Treaty.
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.
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.
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.
August 31 - IAEA announces Iran has not met 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 new arms and financial sanctions against Iran.
April 18 - IAEA says Iran has begun making nuclear fuel in its underground uranium enrichment plant.
May 23 - A confidential IAEA report says Iran has not suspended enrichment-related work.
Aug 21 - Iran and the IAEA say they agreed a timeline for answering outstanding questions about Iran’s nuclear program.
Oct 20 - Saeed Jalili is named to replace chief nuclear negotiator Ali Larijani, who resigned.
Oct 24 - The U.S. imposes new sanctions on Iran and accuses Revolutionary Guard of spreading weapons of mass destruction.
Nov 2 - Britain, France, Germany, the U.S., Russia and China agree to push ahead with a third round of tougher sanctions.
Nov 15 - IAEA says Iran has made important strides towards transparency but it remains unable to ascertain Iran does not have a secret, parallel military enrichment program.
Nov 30 - European Union expresses disappointment with Iran after talks with its main nuclear negotiator in London.
Dec 1 - World powers meeting in Paris failed to reach a decision on further sanctions on Tehran, a French diplomat said.
Writing by David Cutler, London Editorial Reference Unit; Editing by Matthew Tostevin