Iran's team which was led by Abbas Araqchi, Deputy Foreign Minister, started talks with the American delegation of negotiators led by Under Secretary of State for Political Affairs Wendy Sherman.
The two teams conducted compact and broad discussions on Thursday as well.
They will continue talks tomorrow and then foreign inistry deputies of the 5+1 member states will join them for the final meeting.
On Wednesday, Iran's Foreign Minister Mohammad Javad Zarif met with his American counterpart John Kerry in Geneva.
He then visited Berlin, Brussels and Paris to exchange views with foreign ministers of Germany and France as well as the European Union Foreign Policy Chief Federica Mogherini.