"We assume that the Russians will not stop working with us due to the American move to end nuclear sanctions waivers," Behrouz Kamalvandi, the spokesperson for the Atomic Energy Organization of Iran, told reporters in Tehran, ISNA reported on Monday.
His comments came after Russian state nuclear company Rosatom suspended work on revamping a factory at the Fordow nuclear complex due to an issue with uranium compatibility.
Kamalvandi said the Russian decision has nothing do with sanctions waivers and is a technical issue, according to Financial Tribune.
"We held talks with the Russians about seven or eight days ago. Technically speaking, uranium enrichment and the production of stable isotopes cannot be carried out in the same place," he added.
In November, the United States said it would cease waiving punitive sanctions related to the Fordow plant from Dec. 15—a move Russia condemned—after Tehran resumed uranium enrichment at the underground site.
Britain, France and Germany have sought to salvage the 2015 nuclear pact—under which Iran undertook to curtail its uranium enrichment program in return for relief from sanctions—since the US withdrew last year.
But the three European powers have failed to make good on the trade and investment dividends promised to Iran under the deal, as they have been unable to shield it from renewed US sanctions that have strangled its vital oil trade.
That has prompted Iran to reduce its compliance with the accord—officially known as the Joint Comprehensive Plan of Action—step by step.
It has already hit back four times with countermeasures, exceeding the deal's limits on nuclear enrichment purity and stockpiles of enriched uranium as well as research and development, including on the advancement of centrifuges used to enrich uranium. In the latest move, it resumed uranium enrichment at Fordow.
Iranian officials say measures are "reversible" if the European signatories fulfill their obligations and secure Tehran's economic benefits under the agreement.
Kamalvandi said Iran and Russia are holding meetings to discuss some "alternative" paths to continue their technical cooperation.
"It should also be noted that, technically speaking, we can continue to produce stable isotopes without the help of the Russians. However, from the political perspective, it would be better to have them on our side."
He added that more information about nuclear cooperation with Russia will be provided to the public in due time.