The head of the United Nations nuclear agency says he is pushing for access to the rooftops of reactors at the Zaporizhzhia nuclear power plant in Ukraine, where Ukrainian officials accuse Russia of planting explosives.
Russian authorities in turn accused Ukraine of planning to sabotage the plant.
Neither side has provided any evidence for their claims of an imminent threat.
The plant was seized by Russia in March 2022, in the first weeks of the war in Ukraine, raising fears of a nuclear accident.
Russian officials have cited security concerns in granting only limited access to officials from the International Atomic Energy Agency.
Wrapping up a four-day visit to Japan, IAEA director general Rafael Mariano Grossi told the Associated Press that the IAEA had recently gained access to more of the site, including the cooling pond and fuel storage areas.
Ukrainian officials had said those areas were mined by Russian authorities but the IAEA found they were not, Grossi said.
“It’s like a conversation, and I’m pushing to get as much access as possible,” he said,
“I’m optimistic that we are going to be able to go up and see” the rooftops of the reactors.
Ukrainian President Volodymyr Zelenskiy alleged on Tuesday that Russian troops placed “objects resembling explosives” atop several power units to “simulate” an attack as part of a false flag operation.
The “foreign objects” were placed on the roof of the plant’s third and fourth power units, the General Staff of Ukraine’s armed forces claimed.
In Russia, Kremlin spokesman Dmitry Peskov this week called the situation at the nuclear plant, which is Europe’s largest, “quite tense” and accused Ukraine of planning an attack.
The United Nations atomic watchdog has repeatedly warned of the possibility of a radiation catastrophe like the one at Chernobyl, about 480km to the northwest, where a reactor exploded in 1986.
The Zaporizhzhia plant has been shelled numerous times since the war began.
Regular power outages have made it impossible to operate the plant safely and its six reactors have been shut down to minimise the threat of a disaster.
One expert said that even if explosive materials were found on the plant’s roofs, they were unlikely to cause extensive damage.
“These reactors are designed to withstand the type of implosions from a plane crash, and there is a belief that they would withstand shelling for example,” Chatham House researcher Patricia Lewis said.
Grossi said the IAEA had modelled the possible environmental impact of an explosion or bombing at the plant.
“You have enough nuclear material to create quite a disastrous situation in the worst scenario but then there are different alternatives that could happen,” he said.
The IAEA has officials stationed at the plant, which is still run by its Ukrainian staff.