Qatar’s foreign minister headed to Moscow on Sunday for talks on Russia’s role in a new Iran nuclear deal and on the Ukraine conflict, according to reports. 

A source with knowledge of the visit told AFP that Sheikh Mohammed bin Abdulrahman Al Thani would meet Russia’s Foreign Minister Sergei Lavrov and other top officials on Monday.

Hours before leaving to Russia, Thani spoke with US Secretary of State Antony Blinken and Iran’s Foreign Minister Hossein Amir-Abdollahian about Russia’s new demands on the Iran talks, which Moscow has linked to sanctions imposed over its invasion of Ukraine.

Last week, Lavrov created uncertainty over the nuclear talks, saying Moscow wanted a written US guarantee that its trade, investment, and military-technical cooperation with Iran would not be hindered by Western sanctions imposed since it invaded Ukraine.

Kremlin’s demands have aroused the disbelief and discontent of Iranian officials. Following the announcement, Iran’s Foreign Minister Hossein Amirabdollahian said that Tehran would not allow “any foreign elements to undermine its national interests”, the Iranian semi-official news agency Tasnim reported.

Earlier on Sunday, a senior State Department official told the Wall Street Journal that the US will not negotiate exemptions to Ukraine-related sanctions on Russia to save the nuclear deal.

The Russian demands are seen as obstructing 10 months of negotiations in Vienna that have brought western countries agonisingly close to renewing a 2015 deal on regulating Iran’s nuclear programme.

A former Iranian diplomat, who didn’t want his name to be disclosed because of likely repercussions, told Middle East Eye on Wednesday that the Russian demand was “weird”.

He said the most important parties were Iran and the United States, and if they wanted to sign there was nothing Russia, nor the other countries involved in talks, could do about it.

Asked about the importance of Russia in the so-called JCPOA deal, since Moscow is tasked with shipping 20 percent of enriched uranium out of Iran, he added: “It is no big deal, the US and Europe can easily find another country to do that for Iran.”

Russia’s would also be responsible to assist in the conversion of Iran’s Fordow nuclear plant into a research facility if a deal was reached.

On Saturday, France, Britain and Germany warned Moscow that its demands to have its trade guaranteed with Iran risked the collapse of an almost-completed nuclear deal.

Russia, along with China, has been one of Iran’s closest partners in the talks with world powers.

Qatar, a neighbour to Iran, has stepped up its efforts calling on the United States and Iran to move close to a new deal.

The source added that Doha was not mediating in the Ukraine conflict but said it was ready to do if asked.