According to Western officials, the first discussions between Iran and 06 world powers on Tehran's nuclear programme have ended on a positive note.
But some diplomats said there was still a long way to go, and specific actions were needed from Iran.
The talks in Istanbul yesterday were the first for 15 months.
The next round will take place in Baghdad on the 23rd of May.
Iran says its programme is peaceful, but critics suspect it of seeking to develop a nuclear weapons programme.
The European Union's foreign policy chief, Catherine Ashton, described the talks as "constructive and useful".
Speaking at the end of the talks between the 06 countries - the US, UK, France, China, Russia and Germany including Iran, Baroness Ashton said that future discussions would be guided by the "principle of a step-by-step approach and reci-pro-city".