Spokesman of the Atomic Energy Organization of Iran (AEOI) Behrouz Kamalvandi said the talks between Tehran and the six world powers is moving ahead, but with difficulty. "The negotiations are on a path that we can say they move forward with difficulty," Kamalvandi said in an interview with the Islamic republic news agency on Saturday. "It seems that the next round of negotiations will specify the path of the talks and (the possibility of) reaching a final agreement," he added. The fourth round of talks between Iran and Group 5+1 (the five permanent UN Security Council members plus Germany) for reaching a comprehensive agreement will be held on May 13 in the UN headquarters in Vienna. On November 24, Iran and the Group 5+1 sealed a six-month Joint Plan of Action to lay the groundwork for the full resolution of the West’s decade-old dispute with Iran over the latter's nuclear energy program. Kamalvandi also pointed to the "positive cooperation" between Iran and the International Atomic Energy Agency, and said Tehran is committed to its undertakings based on the UN nuclear watchdog's rules and expects the IAEA to act upon its undertakings and responsibilities. Early in February, the AEOI and the IAEA released a 7-article memorandum of understanding (MoU) on continued cooperation in the future. The AEOI-IAEA agreement was reached after two days of intensive talks in Tehran. The AEOI and the IAEA also issued a joint statement after their bilateral talks. The statement said, "The Islamic Republic of Iran and the IAEA held constructive technical meetings on February 1-2 within the framework of cooperation that was agreed by both sides in November." It said the two sides "reviewed progress in implementing the action plan as agreed by them three months ago" and "Iran has implemented the practical steps foreseen in the agreement". Director-General of the IAEA Yukiya Amano and Head of the AEOI Ali Akbar Salehi had earlier signed a joint statement in Tehran in November which presented a roadmap for future cooperation to resolve the remaining issues between the two sides. The statement endorsed by the two top nuclear official specified 6 topics for cooperation and its content was fully implemented by Iran in almost three months.