Iran and the EU have appeared to make progress in resolving outstanding differences on how to implement a landmark nuclear deal, but the United States said discussions were not yet finalised.
Iran's deputy foreign minister, Abbas Araqchi, met a senior EU official in Geneva on Friday to iron out details of the November 24 accord under which Iran agreed to curb its most sensitive nuclear work in return for sanctions relief.
After the meeting, he said that the sides had found "solutions for every difference" but more consultations were needed before an agreement could be announced.
"Now we are taking the solutions... home, all of us," Araqchi said. "Hopefully tomorrow we can either confirm or not, but hopefully confirm."
A spokesman for the EU, Michael Mann, said "very good" progress was made "on all the pertinent issues", but added that results of the talks still had to be validated by more senior officials.
EU negotiates with Iran on behalf of six world powers - the US, Russia, China, France, Britain and Germany - in diplomatic efforts related to Tehran's nuclear work.
No final deal
State Department spokeswoman Jen Psaki said the technical talks were making good progress but reports that a deal had been finalised were inaccurate.
"There have been a few outstanding issues, but at this point, the reports that everything has been finalised are incorrect," she said.
The seven countries need to agree when the nuclear accord goes into effect, when the EU and the US ease economic sanctions in return for Iranian nuclear concessions, including verification of Iranian action.
Diplomats have said the sides aim to start implementing the agreement on January 20, to allow EU foreign ministers, scheduled to meet that day, to approve the suspension of EU sanctions covered by the deal.
Meanwhile, the White House declined on Friday to renew its previous prediction that a Senate bill slapping new sanctions on Iran, which it fears could scupper nuclear talks, would not pass the Senate.
President Barack Obama's spokesman Jay Carney, however, warned that the bill would be detrimental to the drive to resolve the nuclear showdown with Tehran.
"I think that we remain hopeful that Congress will not pass such a sanctions bill because of the negative effect that would have on the ongoing negotiations and the potential to resolve this peacefully," Carney said.
Last December, the White House said Obama would veto the bill if it was passed.