The head of the United Nations nuclear watchdog said he was “deeply concerned” that the Zaporizhia nuclear power plant could be hit during Ukraine’s counter-attack against Russia.

The factory is very close to active fighting, “so we’re concerned that there could be — I mean, obviously, mathematically — the odds of a hit,” said the head of the International Atomic Energy Agency Raphael Grossi.

Speaking in Kiev after meeting with Ukrainian President Volodymyr Zelensky, Grossi said the IAEA was trying to “prevent something bad” and that it is still a “relatively dangerous situation.”

Prior to his visit to the plant, the IAEA chief said he would be at the facility for a few hours. There is a rotation of IAEA experts returning to Vienna and being replaced by a new team, he said.

“We’re expanding the team, so we’re trying to make our process as visible, as efficient as possible to avoid a nuclear accident”he said.

On Sunday, the IAEA said it needed access to a site near the Zaporizhia plant to measure the water level at the reservoir’s pumping site, Nova Kahovka. This is crucial because the reservoir, which supplies cooling water to the nuclear plant and is vital to its safety, lost much of its water after the dam collapsed last week.

The IAEA said it would have to determine exactly how much water was lost.