Addressing days of feuding with Kyiv, the international Atomic Energy Agency head said the “highest levels” of the Ukrainian government had requested a safety mission to the sprawling Zaporizhzhya nuclear plant, now held by Russian troops.

At the same time, Ukraine’s nuclear regulator and Energoatom, the power plant operator, have both vociferously discouraged such a visit until Russian forces are driven from the plant, the IAEA’s Rafael Grossi said in a speech to the agency’s board, World Nuclear News reported.

“This mission is not a matter of wanting or wishing, it is an obligation on the side of Ukraine and on the side of the IAEA,” Grossi was quoted by WNN as saying. “The IAEA will go to Zaporizhzhia nuclear power plant under the legally binding safeguards agreement that Ukraine has with the IAEA.”

For the past several weeks, Grossi has been appealing to send a safety mission to the Zaporizhzhya plant — the largest of its kind in Europe — which fell into Russian hands after an attack on March 4.

Since then, Ukrainian plant workers continue to monitor its six Soviet-built reactors under Russian guard. Several officials from Rosatom, Russia’s state nuclear corporation, are said to be onsite giving orders – a situation Grossi called “untenable” in his remarks.

Grossi has approached both sides seeking permission for a technical and safety visit to the plant — but both sides have insisted the IAEA mission be carried out on their authority alone.

The squabble has led to testy remarks from Energoatom, which has criticized Grossi’s possible visit as “legitimizing” Russian occupation of the plant.

Moscow has meanwhile been coy about its plans for the enormous plant, whose six reactors supply one fifth of Ukraine’s electricity. While Rosatom head Alexey Likhachev has insisted he does not intend to take full operational control of the plant, other Russian officials have suggested Kyiv should be forced to pay Moscow for the electricity the plant generates.

Energoatom has questioned the IAEA’s visit to Zaporizhzhya on logistical grounds, saying: “Nobody from Ukraine invited them there, first of all for security reasons” and that the “only way to expedite the visit of IAEA experts” is if the IAEA’s call for the withdrawal of Russian troops and weapons from plant was heeded, as happened at Chernobyl, WNN reported.

“The current situation is untenable,” Grossi said in his remarks, according to WWN. “Every day it continues; every day that vital maintenance work is delayed; every day that supply chain interruptions cause a break in the delivery of vital equipment; every day the decision-making ability of Ukrainian staff is compromised; every day the independent work and assessments of Ukraine’s regulator are undermined; the risk of an accident or a security breach increases.”