Iranian negotiators have met with officials from the P5 +1, comprised of the US, UK, France, China, Russia and Germany, to discuss its controversial nuclear programme.
A western official said that the talks in Kazhakstan had been “useful” and another meeting will be held on Wednesday.
The negotiations are expected to centre on incentives offered to Iran, including the easing of sanctions, to ease some of its uranium enrichment.
"The offer addresses the international concern on the exclusively peaceful nature of the Iranian nuclear program, but it is also responsive to Iranian ideas,'' said EU spokesman Michael Mann.
"We've put some proposals forward which will hopefully allow Iran to show some flexibility.''
The new US Secretary of State John Kerry meanwhile warned that Iran’s time would run out eventually, if no diplomatic solution was found.
"The window for a diplomatic solution simply cannot by definition remain open forever. But it is open today. It is open now," he said.
"There is still time but there is only time if Iran makes the decision to come to the table and negotiate in good faith."