Brussels: It is "urgent" that the UN's atomic watchdog be allowed to inspect the Zaporizhzhia nuclear power plant in Ukraine that is under Russian military control, NATO chief Jens Stoltenberg said Wednesday.

Russia's seizure of the plant "poses a serious threat to the safety and the security of this facility (and) raises the risks of a nuclear accident or incident," he told reporters in Brussels.

"It is urgent to allow the inspection by the International Atomic Energy Agency and to ensure the withdrawal of all Russian forces," he said.