Russia's demand for US guarantees may harm nuclear talks, Iran official says

Russia's demand for written US guarantees that sanctions on Moscow would not damage Russian cooperation with Iran is "not constructive" for talks between Tehran and global powers to revive a 2015 nuclear deal, a senior Iranian official told Reuters on Saturday.

The announcement by Russia, which could torpedo months of intensive indirect talks between Tehran and Washington in Vienna, came shortly after Tehran said it had agreed a roadmap with the UN nuclear watchdog to resolve outstanding issues which could help secure the nuclear pact.

"Russians had put this demand on the table (at the Vienna talks) since two days ago. There is an understanding that by changing its position in Vienna talks Russia wants to secure its interests in other places. This move is not constructive for Vienna nuclear talks," said the Iranian official in Tehran.

Demanding written US guarantees that Western sanctions imposed on Russia over the conflict in Ukraine would not damage its cooperation with Iran, Russian Foreign Minister Sergei Lavrov said the limitations had become a stumbling block for the Iran nuclear deal, warning the West that Russian national interests would have to be taken into account.

Lavrov said the sanctions on Russia over the conflict in Ukraine had created a "problem" from Moscow's perspective.

When asked whether Russia's demand would harm 11 months of talks between Tehran and world powers, including Russia, Iran Project Director at International Crisis Group, Ali Vaez said: "Not yet. But it's impossible to segregate the two crises for much longer."

"The US can issue waivers for the work related to the transfer of excess fissile material to Russia. But it's a sign that the commingling of the two issues has started," Vaez said.

All parties involved in Vienna talks said on Friday they were close to reaching an agreement.

"We have agreed to provide the IAEA by the end of (the Iranian month of) Khordad (June 21) with documents related to outstanding questions between Tehran and the agency," Iran's nuclear chief Mohammad Eslami told a joint news conference with International Atomic Energy Agency (IAEA) chief Rafael Grossi.

Grossi arrived in Tehran late on Friday to discuss one of the last thorny issues blocking revival of the pact, which in return for a lifting of economic sanctions limited Iran's enrichment of uranium, making it harder for Tehran to develop material for nuclear weapons.

"It is important to have this understanding ... to work together, to work very intensively," Grossi told the televised news conference.

"Without resolving these (outstanding) issues, efforts to revive the JCPOA may not be possible."

A major sticking point in the talks is that Tehran wants the question of uranium traces found at several old but undeclared sites in Iran to be closed. Western powers say that is a separate matter to the deal, which the IAEA is not a party to, several officials have told Reuters.

Grossi, who also held talks with Iran's foreign minister before returning to Vienna on Saturday, said, "there are still matters that need to be addressed by Iran."

The IAEA has been seeking answers from Iran on how the uranium traces got there - a topic often referred to as "outstanding safeguards issues".

Grossi's trip has raised hopes that an agreement with the IAEA will potentially clear the way for revival of the nuclear pact that was abandoned in 2018 by former US President Donald Trump, who also reimposed far-reaching sanctions on Iran.

Since 2019, Tehran has breached the deal's nuclear limits and gone well beyond, rebuilding stockpiles of enriched uranium, refining it to higher fissile purity and installing advanced centrifuges to speed up output. Iran denies it has ever sought to acquire nuclear weapons.