Iran's Foreign Minister Mohammad Javad Zarif and Head of the Atomic Energy Organization of Iran (AEOI) Ali Akbar Salehi are to meet with US Secretary of State John Kerry and US Energy Secretary Ernest Moniz in Geneva to discuss Tehran's nuclear program, Press TV reported.
According to reports on Sunday, Zarif and Salehi will hold talks with Kerry and Moniz at 08:30 p.m. local time (0730 GMT) in the Swiss city. Their deputies will join them later.
Earlier in the day, Salehi and Moniz held a bilateral meeting to discuss the technical aspects of the Iranian nuclear work as part of the negotiations between Iran and the P5+1 group.
Analysts say the presence of Salehi and Moniz, both of whom are physicists and are graduates of the Massachusetts Institute of Technology (MIT), shows that the negotiations have further moved toward technical issues.
On Friday, the representatives of Iran and the US kicked off a fresh round of intensive talks on the Islamic Republic's nuclear program in Geneva to narrow the remaining gaps ahead of a March 31 deadline for a comprehensive agreement.
Iran and the P5+1 group of world powers - Britain, France, China, Russia, the United States, Germany - are seeking to seal a high-profile political deal by the end of March and to confirm the full technical details of the accord by July 1.
The scale of Iran's uranium enrichment and the timetable for the removal of the anti-Iran sanctions are seen as the major stumbling blocks in the talks.