TEHRAN - Iran and the European Union were locked in last-ditch negotiations Thursday after the clerical regime threatened to resume some of its nuclear activities despite warnings of being hauled before the UN Security Council.
Following is a chronology of major dates in Iran's standoff with the West over its nuclear activities:

-- 2002 --
Dec 12-13: Satellite photographs broadcast by US television stations reveal the existence of nuclear sites at Arak, southwest of Tehran, and Natanz in the centre of the country, which an exiled Iranian oppposition group claims could have a military use. Iran agrees to an International Atomic Energy Agency (IAEA) inspection.

-- 2003 --
Feb 9: Iranian President Mohammad Khatami announces that his country plans to produce its own nuclear fuel for future use in power plants.
Feb 21: IAEA head Mohammed ElBaradei visits Iran to verify Tehran's claims that its nuclear programme is peaceful, contrary to Washington's assertion that the country is preparing to build nuclear weapons.
February to May: IAEA carries out inspections in Iran.
June 16: IAEA says Iran failed to declare some of its nuclear activities, notably buying uranium, but that it was undertaking "corrective measures".
June 19: IAEA requests that Iran sign on to an additional protocol of the Non-Proliferation Treaty (NPT) and allow tougher inspections of its nuclear sites.
July 21: The European Union warns that it would reconsider its economic ties with Iran unless Tehran provides credible guarantees that it is not developing nuclear arms.
Aug 26: Tehran says it will allow a reinforced IAEA inspections regime but wants guarantees that the inspectors will not divulge its military secrets.
A confidential UN report reveals that Iran has developed two kinds of enriched uranium that are not needed for peaceful energy production.
Sept 12: IAEA gives Tehran until October 31 to prove that it is not developing nuclear arms. Tehran rejects the ultimatum.
Oct 21: Following a visit by the foreign ministers of Britain, France and Germany, Iran accepts all the conditions put by the IAEA -- full cooperation with the agency, stricter control of its nuclear activities, a suspension of uranium enrichment and agreement to sign the additional protocol to the NPT.
Oct 23: Iran hands over a report on its nuclear programme to prove that its aims are purely civilian.
Nov 10: An internal IAEA report finds "no proof that Iran is creating nuclear weapons," a conclusion dismissed by the United States.
Nov 26: The IAEA's board of governors adopts a resolution criticising Tehran for failing to live up to its commitments.
Dec 18: Iran signs the additional NPT additional protocol.

-- 2004 --
April 4: Iran denies having any secret nuclear sites.
May 21: Iran hands over a more than 1,000-page report to the IAEA, essentially acknowledging 18 years of deception.
June 1: IAEA claims to have found new traces of enriched uranium that exceeded the levels necessary for civilian energy production.
June 18: The IAEA adopts a resolution condemning Iran's ommissions in reports on its nuclear programme.
July 31: Iran admits to having resumed production of parts for centrifuges that are used for enriching uranium, but insists that it has not resumed its enrichment activities.
Aug 28: Iranian President Mohammad Khatami says the IAEA must accept Iran's right under the NPT to enrich uranium for peaceful purposes.
Sept 1: An IAEA report says a number of Iran's claims concerning its nuclear development are "plausible" but expresses renewed concern over Iran's decision to resume large-scale production of the feed material for enriching uranium.
US Secretary of State Colin Powell says the IAEA report warrants Security Council action.
Sept 14: Iran refuses to accept an unlimited suspension of uranium enrichment and says it will not stop manufacturing centrifuges.
Sept 18: IAEA gives deadline of November 25 for Tehran to reveal all its nuclear activities.
Sept 21: Iran says it has resumed large-scale conversion of uranium yellowcake ore, a step towards uranium enrichment.
Oct 21: Berlin, London and Paris call for Tehran to suspend all uranium enrichment activities to avoid its case being brought before the Security Council, offering incentives for it to do so.
Oct 31: The hardline-controlled Iranian parliament passes bill approving resumption of enrichment activities.
Nov 5-6: Talks in Paris, followed by announcement of "preliminary agreement".
Nov 14: Iran accepts complete suspension of uranium enrichment and related activities while further talks are held.
Nov 22: Suspension of enrichment takes effect, a move hailed by the IAEA, although Iran later says it will resume the activity in future and that it will "never renounce" its right to enrich uranium.
Dec 13: Talks open between Iran and EU.

-- 2005 --
Jan 13: IAEA inspectors visit Parchin site southeast of Tehran, alleged by Washington to be involved in a suspected military part of the nuclear programme.
Feb 13: Iran says it will not give up construction of a heavy water reactor which can be used for military purposes, despite an EU offer of a light-water reactor.
Feb 27: Iran and Russia sign nuclear fuel accord that paves the way for the start-up of the Bushehr plant. Russia will fuel the reactor on condition that Iran sends back spent fuel, which could be reprocessed for weapons use.
March 23: Tehran wants to resume a scaled-down uranium enrichment programme but Europe insists on a complete suspension.
April 30: Tehran says it could resume uranium conversion, a step in the enrichment process.
May 2: Germany sternly warns against a resumption of enrichment activities, saying it would spell the end of negotiations between Tehran and the EU, and pave the way for a referral to the UN Security Council.
May 8: Iran announces steps towards the ratification of the additional treaty to the NPT, but says it plans to resume enrichment.

05/12/2005 12:41 GMT