The bilateral talks precede the meeting of the foreign ministers of the so-called P5+1 group, comprising the United Kingdom, France, China, Russia, the United States and Germany, in the Swiss city of Lausanne scheduled for Sunday.
On Saturday, the foreign ministers of Germany and France, EU foreign policy chief Federica Mogherini arrived in Lausanne for negotiations.
The political part of the comprehensive agreement on Iran's nuclear program should have been agreed upon by March 24. However, during the most recent round of negotiations in Lausanne, the deadlines for reaching the political framework agreement have been shifted.
Assessing the chances of signing the framework agreement by the end of March, Russian Deputy Foreign Minister Sergei Ryabkov said they are "significantly higher than 50 percent."
Tehran and the P5+1 group have been involved in talks aimed at reaching an agreement that will guarantee the peaceful nature of Iran's nuclear activities since November, 2013.
The sides are expected to conclude a final deal on the issue before the start of July, 2015.
Chinese Foreign Minister Wang Yi has arrived in Lausanne, Switzerland to join the P5+1 and Iran talks on Tehran’s nuclear program, a Sputnik correspondent reported Sunday.
According to diplomatic sources, Wang Yi is due to meet his Iranian counterpart Mohammad Zarif and then hold a meeting with US Secretary of State John Kerry.
Later in the day, he will also meet with Russian Foreign Minister Sergei Lavrov.