The intermediate agreement will expire in a month, the source told ITAR-TASS on Friday.
The Western delegation expressed hope for progress in coordinating the text of future comprehensive agreement.
According to earlier reports, the talks may last for 20 days.
“Everything looks positive. There are signs of progress,” he said.
“The current round of talks can end today,” Ryabkov said.
The P5+1 is a group of countries, which in 2006 joined the diplomatic efforts with Iran regarding its nuclear program. The term refers to the five permanent members of the UN Security Council plus Germany, namely the United States, Russia, China, United Kingdom, France, and Germany.