European Union foreign policy chief Catherine Ashton will meet with Iran's chief nuclear negotiator, Said Jalili, in Istanbul on May 15, EU officials said.
Ashton, who represents the five permanent members of the UN Security Council and Germany, will be following up on the April 5-6 talks in Almaty, Kazakhstan.
Also on May 15, the International Atomic Energy Agency is scheduled to resume talks with Iran about its disputed nuclear program.
Much of the international community is concerned that Iran is seeking to build nuclear weapons.
Tehran insists the program is exclusively peaceful.
Based on reporting by dpa and AFP