World powers will present Iran with an updated and "good" offer at talks this week on its nuclear programme, although hopes for a breakthrough appear slim.
Talks aimed at curbing Tehran's nuclear drive start on Tuesday in Kazakhstan, with the so-called 5+1 world powers represented by the European Union sitting down with an Iranian team led by negotiator Saeed Jalili.
A spokesman for European Union foreign policy chief Catherine Ashton, who leads the talks with Iran on behalf of the powers, said on Monday that Tehran should understand that there was an "urgent need to make concrete and tangible progress" in Kazakhstan.
"We have prepared a good and updated offer for the talks, which we believe is balanced and a fair basis for constructive talks," said the spokesman for EU foreign policy chief Catherine Ashton.
"The offer addresses international concerns... on the nature of the Iranian nuclear programme, but is also responsive to Iranian ideas.
"We hope that Iran will seize this opportunity and come to the talks with flexibility and commitment to make concrete progress towards a confidence-building step."
A source close to the negotiations said the offer would still insist that Iran halts enriching uranium to 20 percent, shuts down its controversial Fordo uranium enrichment plant and sends abroad all uranium already enriched to 20 percent.
Concessions in return
"This still forms the basis of the demands of the 5+1 group," said the source who asked not to be identified.
Another Western source said the powers could discuss lifting sanctions on Iran in exchange for specific concessions, although the source provided no further details.
In Washington, a top US official refused to be drawn on the details of what he called a "serious, updated proposal" to Iran saying "we need to let the negotiators do their jobs."
But State Department acting deputy spokesman Patrick Ventrell revealed that the proposal "does include reciprocal measures" to encourage Iran "to make concrete steps to begin addressing the international community's concerns."
Earlier reports said the P5+1 group could consider easing sanctions on Iran's gold and precious metals trade.
World powers have until now wanted Iran to take the first step and only then reward it by easing the various sanctions regimes in place.
However, Iranian negotiator Jalili said at the weekend that Tehran would not go beyond its obligations or accept anything outside its rights under the non-proliferation treaty (NPT).
The 5+1 world powers are the United States, Britain, China, France, Russia and Germany.