Iran says Russia has not retreated from cooperating with Iran at Fordow enrichment facility, rejecting claims that a recent halt in the Russian contribution has been prompted by US sanctions.

Foreign Ministry spokesman Abbas Mousavi said Monday the cooperation has been halted because of “technical” issues which are being sorted out by Iranian and Russian experts.
The United States restored sanctions against Iran after unilaterally leaving a multilateral nuclear agreement to which Russia is a signatory.
In November, Washington cancelled a waiver for international cooperation in Fordow, including Russia's reconfiguration of the enrichment facility to produce stable isotopes used in clinical studies.
Iran, meanwhile, has resumed injecting gas to centrifuges at the facility as part of its decision to scale back its commitments to the nuclear accord.
Moscow has said it needs time to react to the new circumstances at Fordow. Russia contends that gas injection to the centrifuge cascades in the same premises where stable isotopes are to be produced has hampered the original plan of reconfiguration.
“The main reason for the halt is simultaneity of two operations. The Russian side is trying to find out whether both can be undertaken at the same time,” Mousavi said on Monday. 
Russian nuclear reactor builder Rosatom said earlier this month that it had stopped reconfiguration work at Fordow.