Russian Foreign Minister Sergei Lavrov and his Iranian counterpart Hossein Amir Abdollahian held a phone conversation on Monday to discuss the 2015 Iran nuclear deal.

The two countries' top diplomats reaffirmed their common position to restore the nuclear deal in its original balanced text, approved by the United Nations Security Council, the Russian Foreign Ministry said in a statement.

They stressed that this is the only correct way to ensure the rights and interests of all participating parties in the deal, formally known as the Joint Comprehensive Plan of Action (JCPOA).

Multilateral negotiations to save the Iran nuclear deal resumed on November 29 in Vienna of Austria. 

Russian Deputy Foreign Minister Sergei Ryabkov told reporters on Monday that Russia had reason to expect some progress on the revival of the 2015 nuclear deal with Iran and that the likelihood of reaching an agreement had increased.

Talks have resumed in Vienna to try to revive the nuclear pact, with both sides trying to gauge the prospects of success after the latest exchanges in the stop-start negotiations.

The 2015 nuclear deal will very soon become "an empty shell" without progress, senior British, French and German diplomats said on Monday, offering a pessimistic assessment of the ongoing efforts. 

"As of this moment, we still have not been able to get down to real negotiations," the diplomats from the so-called E3 said in a statement about the Vienna nuclear negotiations in which they are shuttling between U.S. and Iranian officials.

"Time is running out," one of the officials said.

(With input from agencies)