Here is a chronology of the main events since many in the West became concerned about Iran's nuclear program.

2002

Dec 12-13: Satellite photos broadcast on US television show the existence of two nuclear sites at Arak and at Natanz, which American media reports say are intended for military purposes. Iran permits an inspection by the UN nuclear watchdog, the International Atomic Energy Agency (IAEA).

2003

Feb 9: Iran President Mohammad Khatami annouces that his country will produce its own nuclear fuel for future nuclear power plants.

Feb 21: IAEA director general, Mohamed El Baradei, visits Teheran to verify that Iranian nuclear program is designed for peaceful purposes and not to make an atomic bomb.

Feb to May: Series of inspections by the IAEA.

June 19: IAEA asks Iran to accept an additional protocol of the Nuclear Non-Proliferation Treaty (NPT) that would allow for inspections of all nuclear sites, including those not declared by Tehran.

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: A UN report finds two types of enriched uranium in Iran, which are not needed for civil nuclear programs.

Sept 12: The IAEA gives Iran until October 31 to prove that it is not developing a nuclear weapons program. Tehran rejects the ultimatum.

Oct 21: During an unprecedented visit to Iran by the foreign ministers of France, Germany and Britain, Tehran agrees to cooperate "totally" with the IAEA, including the suspension of its uranium enrichment program.

Nov 10: An internal IAEA report finds that there is no proof Iran is trying to make a nuclear weapon, a conclusion dismissed by the United States.

Nov 26: The IAEA adopts a resolution criticizing the Islamic Republic for failing to meet its obligations.

Dec 18: Tehran signs the additional NPT protocol.

2004

April 4: Iran denies having secret nuclear sites and maitains that its uranium conversion site at Isfahan does not violate its agreements.

June 1: IAEA says it has discovered in Iran traces of enriched uranium at a level higher than needed for civilian purposes.

June 18: IAEA adopts resolution severely criticizing Iran's omissions.

Sept 1: An IAEA report raises concerns about Iran's intention to continue with its tests related to uranium enrichment.

Sept 18: IAEA tells Iran to come clean on all its nuclear activities by November 25 and reinstate its suspension of uranium enrichment activities.

Sept 21: Iran announces it has begun large-scale uranium conversion.

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.

Nov 14: After Paris talks, Iran agrees to suspend "temporarily" its uranium enrichment activities in exchange for talks with the European Union on nuclear, technological and commerical cooperation.

Nov 22: Suspension of uranium enrichment activities in Iran goes into effect.

Nov 30: Iran announces that it will resume enrichment saying it never promised to stop it permanently.

Dec 13: Opening of negotiations with the three large EU countries - France, Germany and Great Britain.

2005

Jan 13: IAEA inspectors visit military site at Parchin, Iran.

Feb 13: Iran refuses to stop the construction of a heavy-water reactor capable of being used for military purposes, despite a European offer for a light-water reactor.

March 23: According to diplomatic sources, Iran proposes an enrichment program on a limited scale to the Europeans, who still insist the Tehran permanently stop the program.

April 30: Iran announces it can restart uranium conversion at Ispahan in a few days, a preliminary step toward enrichment.

May 11: The Europeans formally warns Iran against restarting sensitive nuclear activities which could jeopardize the negotiations. British Prime Minister Tony Blair threatens to take Iran before the UN Security Council.

May 19: Iran warns that its decision is "irreversible.".

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