Following is a timeline of key developments in the international standoff over Iran's nuclear programme, after Tehran said Tuesday it had succeeded in enriching uranium.

-- 2002 --

Dec 12-13: Satellite photographs shown on US television reveal the existence of nuclear sites at Arak, southwest of Tehran, and Natanz in central Iran, which US media says may have a military use. Iran agrees to International Atomic Energy Agency (IAEA) inspection.

-- 2003 --

Feb 9: Iran's President Mohammad Khatami says uranium deposits have been discovered in Iran and Tehran is building two factories to convert the ore into nuclear power station fuel.

Aug 26: A confidential UN report reveals Iran has developed two kinds of enriched uranium not needed for peaceful energy production.

Nov 10: An internal IAEA report states: "At the moment, there is no proof that Iran is creating nuclear weapons," a conclusion the United States disputes.

Dec 18: Iran signs an additional protocol to the nuclear Non-Proliferation Treaty allowing unannounced inspections of nuclear sites. Protocol must still be ratified by parliament.

-- 2004 --

June 1: The IAEA claims to have found new traces of enriched uranium that exceed the levels necessary for civilian energy production.

July 31: Iran admits to having resumed production of parts for centrifuges used for enriching uranium, but insists it has not resumed enrichment.

Sept 21: Iran says it has resumed large-scale conversion of uranium ore.

Nov 14: Iran accepts complete suspension of uranium enrichment activities, including the precursor process of conversion, while talks are held.

Nov 22: Suspension of enrichment takes effect.

Dec 13: Talks open between Iran and European Union.

-- 2005 --

Feb 27: Iran and Russia sign a nuclear fuel accord that paves the way for the start-up of the Bushehr nuclear plant. Russia will fuel the reactor on condition Iran sends back spent fuel.

Aug 3: Hardline President Mahmoud Ahmadinejad takes office.

Aug 5: Tehran rejects an EU offer of a broad package of incentives aimed at ending the standoff.

Aug 8: Iran resumes uranium conversion work at Isfahan and later removes IAEA seals, as talks with the EU are suspended.

Aug 11: IAEA board adopts resolution demanding Iran halt nuclear fuel work but non-aligned nations express reservations.

Aug 12: US President George W. Bush refuses to rule out the use of force against Iran.

Sept 2: IAEA releases a critical report saying Iran has continued sensitive nuclear fuel work and calls for full transparency.

Sept 20: Iran threatens to resume enrichment, prevent UN inspections of its nuclear sites and abandon the NPT if it is referred to the Security Council.

Sept 24: The IAEA passes a resolution that reserves the right to send Iran's case to the UN Security Council, but Russia and China abstain.

Nov 11: Russia presents a plan, endorsed by the European Union and agreed to by the United States, that would allow Iran to continue uranium enrichment but on Russian soil.

-- 2006 --

Jan 3: Iran announces the resumption of nuclear research activities that had been suspended for two years. The IAEA urges it to continue the moratorium.

Jan 7: Talks between Russia and Iran on the Moscow proposal end without a result.

Jan 10: Iran removes IAEA seals placed on enrichment-related equipment at Natanz, provoking a wave of international condemnation.

Jan 12: EU negotiators Britain, France and Germany call for an emergency IAEA meeting for February 2-3, saying the time has come for the UN Security Council to become involved.

Jan 27: US President George W. Bush voices public support for the Russian proposal. Tehran rejects it as "not sufficient" for Iran's nuclear needs.

Jan 31: The five permanent UN Security Council members plus Germany agree to report Iran to the body but to postpone action until March. The IAEA says Iran has begun research relating to uranium enrichment.

Feb 4: The IAEA votes by a large majority to report Iran to the Security Council, leaving the door open to sanctions. It puts off any UN action to allow time for diplomacy before a regular March 6 IAEA meeting. Bush sees it as a sign the world "will not permit" nuclear weapons for Tehran. Iran promptly retaliates by saying it will limit UN nuclear inspections.

Feb 6: Iran says it has formally notified the IAEA of its decision to resume full-scale uranium enrichment work. UN chief Kofi Annan urges Tehran to return to the negotiating table.

Feb 13: Iran has begun putting uranium feedstock gas into centrifuges for enrichment, diplomats say in Vienna.

Feb 14: Tehran says it has begun small-scale enrichment at Natanz.

Feb 26: Iranian-Russian agreement in principle to create joint entity to carry out enrichment in Russia.

March 1: Talks with Moscow fail after Iran insists on continuing to enrich on its own soil.

March 3: Iran-EU3 talks collapse. Iran proposes two-year moratorium on industrial enrichment but insists on continuing research at Natanz.

March 8: IAEA submits case to Security Council.

March 29: Security Council gives Iran 30 days to suspend enrichment. Tehran defies demand, proposes "regional consortium."

April 3: Iran begins military maneuvers in Persian Gulf, including testing of new missiles, and warns "enemies" against attack.

April 11: Ahmedinejad says Iran has joined the atomic club and calls for acceleration of program, as officials confirm successful enrichment.

- White House says Iran moving in "wrong direction"

April 12: Russia and Germany echo US position, and Israel calls nuclear Iran threat to whole world.

© Iranian.ws