Talks between world powers and Iran on its nuclear programme have ended without agreement, with the European Union saying their positions remain far apart.
Over two days of talks in Almaty, the capital of Kazakhstan, Iran was asked to give up work on its most sensitive nuclear activities in return for an easing of sanctions.
However, Iran said it was up to the world powers to demonstrate willingness to take confidence-building steps.
World powers suspect Iran of a covert nuclear weapons programme. Tehran insists its intentions are peaceful.
Iran is negotiating with comprising the five permanent members of the UN Security Council: Britain, China, France, Russia and the United States plus Germany.
EU foreign policy chief Catherine Ashton confirmed no deal was reached.
"It became clear that the positions... remain far apart on the substance," she said on Saturday.
We have therefore agreed that all sides will go back to (their) capitals to evaluate where we stand in the process," she added.
"I think the first hurdle is take the proposal that we put on the table and get a real response to all of it...
The challenge is to get real engagement so that we can move forward with this."
Russian Deputy Foreign Minister Sergei Ryabkov confirmed there had been a "lack of results".
"Unfortunately we were unable to achieve a breakthrough and are still on the threshold," he was quoted as saying by Russia's Interfax news agency.
AFP reports he also said no time or place for the next talks had yet been agreed.
At a previous round of talks in Kazakhstan in February, the UN group tried to push Tehran to halt production and stockpiling of uranium enriched to 20%.
They also demanded Iran shut down the Fordo underground enrichment facility.
In return, the world powers suggested an easing of tough economic sanctions imposed on Iran.
The BBC reports Iran's economy has been squeezed, with oil revenue slashed, the currency nose-diving in value and unemployment growing.