“I can’t predict how many hours it will take to resolve this situation. But all parties are of the opinion that this matter will be resolved in the coming days,” negotiator Sergei Ryabkov told the Russian TASS news agency.

He added that the text Iran and the P5+1 world powers were working on to outline the deal was “91 percent finished.”

Russia’s deputy foreign minister also praised Thursday’s visit to Tehran by the head of the International Atomic Energy Agency (IAEA), Yukiya Amano, which Ryabkov said helped to bring “greater clarity” to the negotiations.

Ryabkov himself was to leave Vienna, where the the negotiations have been taking place, on Thursday.

The Kremlin meanwhile announced that Russian President Vladimir Putin and his Iranian counterpart Hassan Rouhani are to meet in the Russian city of Ufa next week, during the July 9-10 Shanghai Cooperation Organisation summit.

“We are indeed preparing such a meeting,” Kremlin spokesman Dmitry Peskov was quoted as saying by Russian news agencies.

Iran and the P5+1 group — the United States, China, Russia, Britain, France and Germany — have effectively given themselves until Tuesday to reach the landmark nuclear deal.

The P5+1 are seeking to finalise a long-sought accord which will put a nuclear bomb beyond Iran’s reach, in return for lifting biting sanctions against the Islamic republic.

It would end a 13-year standoff over Iran’s suspect nuclear programme, and draw the curtain on almost two years of intense negotiations which resumed in earnest after Rouhani came to power in August 2013.