(Bloomberg) -- The Kremlin’s top diplomat said he expects world powers will salvage the landmark accord limiting Iran’s nuclear activities in exchange for sanctions relief as the latest round of talks grinds on.

The comments by Russian Foreign Minister Sergei Lavrov came as his Iranian counterpart meets officials in China, which has hosted a series of meetings this week with top Middle East envoys to discuss regional security and economic cooperation. 

The eighth round of negotiations to reboot the 2015 nuclear accord -- scuttled almost four years ago by the Trump administration -- is concluding its third week in Vienna. 

“There’s real progress,” Lavrov told reporters on Friday in Moscow. “We are expecting an agreement to be reached.” 

Russia’s optimism followed words of caution by U.S. Secretary of State Antony Blinken on Thursday, when he told National Public Radio in an interview that just weeks remain for sides to reach an accord. U.S. officials have suggested Iran’s rapidly expanding uranium-enrichment program could soon render the accord obsolete. 

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Chinese officials, meanwhile, invited Iranian Foreign Minister Hossein Amirabdollahian to a meeting on Friday to discuss “strategic issues,” according to Iran’s state-run Press TV. Among the topics being discussed with Chinese Foreign Minister Wang Yi is a 25-year bilateral agreement designed to enable billions of dollars of investment in the Persian Gulf country. 

Some analysts have named China the key player that will decide the outcome of the nuclear talks, which also involve France, Germany and the U.K. Beijing’s deepening cooperation with Tehran in the face of U.S. sanctions has given the Islamic Republic’s government an economic escape route. 

China remains a key customer of Iranian oil, with it imports of crude from both Iran and Venezuela -- also heavily sanctioned by Washington -- reaching a three-year high in 2021. The talks in Beijing with Iran follow a visit by Saudi Arabian Foreign Minister Faisal bin Farhan Al-Saud this week, suggesting China is looking to raise its diplomatic profile in the oil-rich region. 

Tehran and Riyadh have recently vowed to work toward re-establishing diplomatic ties and reopening their embassies, which have been shuttered for the past seven years. Last month in Vienna, China said it wanted to increase its role in rejuvenating the nuclear accord. 

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