On Wednesday, Iranian deputy foreign minister and senior negotiator Abbas Araqchi will meet the European Union's deputy secretary general for the external action service, Helga Maria Schmid, to resume drafting the text of a long-awaited deal, known as the Joint Comprehensive Plan of Action (JCPOA).
The EU coordinates diplomacy with Iran on behalf of the Group 5+1 (Russia, China, the US, Britain, France and Germany).
According to Russian Deputy Foreign Minister Sergei Ryabkov and China's representative in the talks Wang Qun, deputies of foreign ministers will not take part in the upcoming round of talks.
Iran and the six powers are in talks to hammer out a lasting accord that would end more than a decade of impasse over Tehran's peaceful nuclear program.
On April 2, the two sides reached a framework nuclear agreement in Lausanne, Switzerland, with both sides committed to push for a final deal until the end of June.