“The issue of the Arak reactor is among the main stumbling blocks,” Russian Deputy Foreign Minister Sergei Ryabkov told RIA Novosti.
The problem of Iran's nuclear centrifuges also remains an issue of concern, according to Ryabkov. The Russian diplomat noted that during the previous rounds of nuclear talks the negotiators agreed that Iran has to limit its uranium enrichment to five percent.
The Russian deputy foreign minister said that he had a number of bilateral meetings with members of the sextet and the Iranian side.
“It feels like there is a common understanding that every effort has to be made to reach an agreement,” the diplomat said.
“Flexibility is needed to form a framework, a carcass of agreement. As of the Russian delegation, we have this flexibility, but also our red lines, which is normal,” Ryabkov added.
Nuclear negotiators representing Iran and the six world powers (Russia, China, the US, Britain, France and Germany) have started a fresh round of talks on Tehran’s civilian nuclear work in New York.
The negotiations are expected to run until at least September 26 on the sidelines of the annual gathering of world leaders at the United Nations General Assembly.
In November 2013, Iran and world powers signed an interim deal in Geneva, which took effect on January 20 and expired six months later on July 20.
In July, Tehran and the six countries agreed to extend negotiations until November 24 in the hope of clinching a final deal.