The Iranian foreign minister has said he held good talks with his US counterpart over Tehran's nuclear programme.
Mohammad Javad Zarif met US Secretary of State John Kerry in Vienna on Tuesday, less than a week before a July 20 deadline on reaching an agreement on ending the dispute.
Despite the "good exchange of views", the US had to take a political decision to end the deadlock, Zarif said, without giving further details, according to Iran's official news agency IRNA.
Iran's top diplomat said serious discussions now needed to take place at the level of political directors, referring to senior foreign ministry officials leading the delegations, the Reuters news agency reported.
Very real gaps
Speaking to reporters after the talks, Kerry said the parties had made "progress" during the negotiations but there were issues that remained unresolved.
"We have all lived up to our obligations but it is clear we have more work to do," Kerry said, adding there remained "very real gaps in key issues."
The secretary of state said he would return to the US to consult President Barack Obama about the state of the negotiations and the possibility of extending talks past the deadline so negotiations could continue.
Iran and six world powers including the United States, France, Russia, China, Britain and Germany, are trying to narrow wide differences over Iran's nuclear programme and reach a long-term agreement by a self-imposed July 20 deadline.
The powers want Tehran to significantly scale back its nuclear enrichment programme to make sure it cannot yield nuclear bombs.
Iran's priority is to get sanctions that have severely damaged its oil-dependent economy lifted as soon as possible.