By Justyna Pawlak and Fredrik Dahl
GENEVA (Reuters) - World powers will press Iran on Wednesday for details of its proposal on resolving their decade-old nuclear dispute during a second day of talks in Geneva.
Western diplomats stress they want Tehran to back up its newly conciliatory language with concrete actions by scaling back its nuclear program and allaying their suspicions it is seeking the capability to make atomic bombs.
Both sides are trying to dampen expectations of any rapid breakthrough at the two-day meeting, the first to be held since President Hassan Rouhani took office, promising conciliation over confrontation in Iran's relations with the world.
"There is still an awful lot of work to be done," said a spokesman for the European Union's foreign policy chief Catherine Ashton, who oversees diplomacy with Iran on behalf of the United States, Russia, China, France, Britain and Germany.
"We have had a certain amount of information from the Iranian side and we will hope to get more detail from them tomorrow," spokesman Michael Mann said after the first day of talks on Tuesday.
His statement suggested Iran had yet to persuade Western nations it was willing to curb the nuclear work and assure them this was purely for peaceful energy production and medical purposes, as Tehran says. In the Tuesday session, negotiators had started discussing the "nitty-gritty" details of Iranian suggestions, Mann said.
Iranian Deputy Foreign Minister Abbas Araqchi said his side had presented a proposal capable of achieving a breakthrough. But he later added it was not possible to tell whether progress was being made. "It's too soon to judge," he told Reuters.
Rouhani's election in June raised hopes in the West that Iran is finally ready to strike a deal. Tehran is anxious to win relief from Western-led sanctions which have crippled its economy, cut its oil export revenues 60 percent and brought about a devaluation of its rial currency.
To achieve this, Iranian negotiators outlined their proposal on Tuesday, without giving any public indication of how far they would go to meet Western demands to curb uranium enrichment.
The White House also warned against expecting quick results from the talks, saying they were complex and technical and that economic pressure on Teheran would remain.
"We certainly want to make clear that no one, despite the positive signs that we've seen, no one should expect a breakthrough overnight," White House spokesman Jay Carney said.
"Although we appreciate the recent change in tone from the Iranian government on this issue, we will be looking for specific steps that address core issues," he added.
At the heart of the dispute are the Iranian efforts to enrich uranium to 20 percent fissile purity, an advance that would bring it close to producing weapons-grade fuel.
Iran has previously spurned Western demands that it abandon such work as an initial step in return for modest sanctions relief, and has repeatedly called for the most painful trade sanctions, such in the oil sector, to be lifted.
Western diplomats have said their demands on the 20-percent uranium must be addressed before progress can be made. But some diplomats acknowledged before the Geneva talks that the offer might be changed substantially depending on what concessions Iran offers.
A U.S. administration official said any possible reduction of sanctions would be "targeted, proportional to what Iran puts on the table".
Israel, Iran's arch-enemy and widely assumed to harbor the Middle East's only nuclear arsenal, has lobbied Western powers not to dilute sanctions before Iran has tackled core concerns - enrichment and lack of transparency - about its nuclear goals.
(additional reporting by Louis Charbonneau, Yeganeh Torbati and Stephanie Nebehay; editing by David Stamp)