What is Iran's current nuclear capability?
Iran has announced that it has successfully enriched uranium to a level where it can begin to produce nuclear fuel.
Iran has repeatedly stated that its nuclear research is for peaceful purposes and is undertaken simply with a view to satisfying growing demands for electricity.
It has had a nuclear programme for nearly 50 years, buying its first reactor from the US in 1959. The shah, then ruler of the country, planned to build 23 nuclear reactors by the 1990s.
Although initially not seen as a back door to a nuclear weapons programme, discoveries by the International Atomic Energy Agency (IAEA) in 2002 and 2003 that Iran was concealing nuclear facilities and materials raised international concerns.
A uranium enrichment plant in Natanz and a heavy water reactor near Arak were kept from the IAEA's attention until 2002.
Subsequent moves by Iran to remove UN monitoring seals and reopen the facility at Natanz met with international outcry.
Uranium can be enriched using a gas centrifuge and according to Akbar Hashemi Rafsanjani, a former Iranian president, Iran is currently undertaking the procedure using a cascade of 164 centrifuges.
However, scientists say a plant involving more than a thousand centrifuges is needed to produce enriched uranium on an industrial scale.
Iran is a signatory to the nuclear Non-Proliferation Treaty.
Why are such facilities of concern?
Iran's nuclear capability puts it in a small league of 10 countries that have known nuclear facilities or weapons.
Iran has uranium enrichment
facilities at a plant in Natanz
By continuing to enrich uranium, it is defying a UN Security Council demand that it stop efforts to do so by April 28.
Mahmoud Ahmadinejad, the president, says Iran has enriched uranium to 3.5% which is sufficient to produce nuclear fuel that can be used for civil energy purposes.
However, highly enriched uranium, at around 90%, can be used for nuclear weapons and many observers fear this is Iran's ultimate intention.
Does Iran have nuclear weapons?
Although Iran is thought to still be years away from producing weapons-grade nuclear material, the US Defence Intelligence Agency has said that Iran could produce a weapon early in the next decade.
Ahmadinejad has said that he intends to scale uranium enrichment up to industrial levels, adding to the concerns of those already suspicious of Iran's nuclear intentions.
Thousands of centrifuges are needed for a workable programme and Iran's nuclear chief says the aim is to be using 3,000 by the end of 2006.
There are fears that if Iran develops nuclear technology, other states may follow suit.
North Korea began a uranium enrichment programme in 1997 and in 2005 announced that it had manufactured an unspecified number of bombs.
There is also the worry that a nuclear-armed Iran would destabilise the region and exacerbate tensions with Israel.
Why is the international community so suspicious?
In a move aimed at nullifying any future Iranian threat, Russia has previously offered to enrich Iranian uranium but on her soil.
Iran has yet to take up the offer and given its claim to have mastered the enrichment process seems even less likely to do so.
Iran's current nuclear strategy was first conceived after the Iran-Iraq war and includes plans for seven 1000MW power plants by 2025.
Ahmadinejad insists Iran's
research is for peaceful purposes
Some see this as an overambitious aim, especially for a country with large oil and gas reserves.
In January 2005, Iran admitted it had been offered a centrifuge enrichment starter kit in 1987 by a network led by AQ Khan, the Pakistani scientist.
Khan, known as the father of the Pakistani nuclear bomb, had previously attempted to supply North Korea with nuclear technology and advice.
In November 2005, Iran admitted that the network had supplied it with information on casting and machining parts of nuclear weapons.