Iran and world powers to hold nuclear talks

Iran and world powers are due to meet in Turkey in a bid to reach a breakthrough on the country's controversial nuclear programme.

Saturday's talks in Istanbul bring Iranian negotiators back to the table with those from the United States, Russia, China, France, Britain and Germany, as well as with Catherine Ashton, the European Union foreign policy chief and the group's main representative.

Both sides say they are ready to work towards resolving the deepening dispute over a nuclear programme that Iran insists is for purely peaceful purposes and the US and its allies say is aimed at developing a nuclear weapon.

Israel has hinted in recent months that it could carry out a pre-emptive strike on Iran to prevent that happening.

The talks are the first to be held between Iran and the world's major powers for 15 months.

On Thursday, Iranian President Mahmoud Ahmadinejad said his country was "standing firm on its fundamental rights and under the harshest pressure will not retreat an iota from its undeniable right".

Few major developments are expected in Istanbul, but the six nations, known collectively as the P5 1, hope it will reopen negotiations and cool tensions.

US President Barack Obama has described this as the "last chance" for diplomacy to work.

Russia said the talks had to be "constructive", and warned both sides not to "overblow the differences" between them.

Iran has signalled some flexibility over halting its enrichment to a fissile purity of 20% , compared with the five percent level required for nuclear power plants, but also suggests it is not ready to do so yet.

Iranian leaders would probably expect to be rewarded with an easing of sanctions if they agreed to scale back their sensitive nuclear work, but Western officials say this is not an issue which is up for negotiation in Istanbul.

"Stopping 20 per cent enrichment would be seen as a gesture to start negotiations, not to lift sanctions," one diplomat at the talks said.

In the end, experts and some diplomats say, both sides must compromise for any long-term deal to resolve the dispute: Iran could keep enriching uranium to low levels in return for accepting much more intrusive UN nuclear inspections.

The West accuses Iran of seeking to develop a nuclear weapons capability. Iran, one of the world's largest oil producers, says its nuclear programme is a peaceful attempt to generate electricity and medical isotopes for cancer patients.

There are currently eight nations that have successfully detonated nuclear weapons. Five are considered to be "nuclear-weapon states" under the terms of the Nuclear Non-Proliferation Treaty. These countries are the United States, Russia, the United Kingdom, France, and China. 

Three other states that are not signatories of the Nuclear Non-Proliferation Treaty have conducted nuclear tests, namely India, Pakistan, and North Korea.  The US’s close ally, Israel also posses nuclear weapons, though it has refused to confirm or deny this, and is not known to have conducted a nuclear test.