The next round of talks on resolving Western concerns over Iran's nuclear programme will take place in Vienna on June 16-20, the European Union announced Tuesday.
After "very long and useful discussions" in Istanbul, the "next formal round ... will be from 16-20 June in Vienna," a spokesman for EU foreign affairs head Catherine Ashton said.
The talks were "very long and useful," spokesman Michael Mann said in a brief statement.
Ashton and Iranian Foreign Minister Mohammad Javad Zarif also recommended that an experts meeting "should take place soon," Mann added.
Ashton and Zarif met in Istanbul from Monday to discuss the next steps towards a final agreement which would resolve Western concerns that Tehran wants to build a nuclear bomb.
Iran has consistently said it is not seeking nuclear weapons but wants an independent nuclear programme to provide energy.
Talks earlier this month in Vienna made no "tangible progress," with a July 20 deadline for a comprehensive agreement looming on the horizon and major issues still outstanding.
The EU's Ashton leads the talks with Iran on behalf of the five permanent members of the UN Security Council plus Germany, known as the P5+1.