The United Nations nuclear watchdog warned of threats to nuclear safety as fighting spikes around Europe’s largest nuclear powerplant in Southeast Ukraine, whose forces are pressing a counteroffensive against Russian troops.

The International Atomic Energy Agency said its experts deployed at the Russia-occupied Zaporizhzhia Nuclear Power Plant reported hearing numerous explosions over the past week, in a possible indication of increased military activity in the region, though they said there was no damage to the plant.

“I remain deeply concerned about the possible dangers facing the plant at this time of heightened military tension in the region,” IAEA Director General Rafael Mariano Grossi warned in a statement issued late Friday.

He noted that the IAEA team was informed that staff at the nuclear power plant had been reduced temporarily to minimum levels due to concerns of more military activity in the area.

“Whatever happens in a conflict zone, wherever it may be, everybody would stand to lose from a nuclear accident, and I urge that all necessary precautions must be taken to avoid it happening,” Grossi said.

The IAEA has repeatedly expressed concern that the fighting could cause a potential radiation accident the facility, which hosts six Soviet-built VVER reactors and numerous spent fuel storage pools. The reactors have been in shutdown mode for months, but they still require power and personnel to operate critical cooling systems and other safety features.

Separately, plant officials told the onsite IAEA experts that drone strikes had taken place in nearby Enerhodar, the plant’s company city where many of its staff and their families live.

The IAEA experts likewise observed the continued presence of mines between plant perimeter fences, though on a walk around, they reported they did not see that any additional ones had been laid.

The experts still have not been granted access to the rooftops of several reactor units to assess whether any military equipment has been placed upon them.