The talks entered the third consecutive day on Wednesday with a meeting between Iranian deputies foreign minister, Abbas Araqchi and Majid Takht Ravanchi, and EU Deputy Foreign Policy Chief Helga Schmid.
Iran and the Group 5+1 (alternatively known as the P5+1 or E3+3) have started the new round of high-profile negotiations in the Austrian capital since June 16.
The five-day negotiations are aimed at drafting a comprehensive deal to resolve the decade-long standoff over Tehran's peaceful nuclear energy program.
Iran and the six world powers inked an interim deal on Tehran’s nuclear program in Geneva last November, which came into force on January 20. The interim deal (the Joint Plan of Action) stipulates that over the course of six months (July 20), the parties will draw up a comprehensive nuclear deal which will lead to a lifting of the whole sanctions on the Islamic Republic.