A nuclear plant in western Russia, where fighting is raging between Russian and Ukrainian forces, is especially vulnerable to a serious accident because it lacks a protective dome that could shield it from missiles, drones or artillery, the head of the U.N. nuclear watchdog said on Tuesday.

Rafael Grossi, director general of the International Atomic Energy Agency, spoke after visiting the plant in the Kursk region, where Ukrainian forces pierced the border in a lightning incursion on Aug. 6 and Russia is still battling to eject them.

Grossi told reporters that the RBMK-type facility — the same model as the Chernobyl plant in Ukraine that witnessed the world's worst civilian nuclear disaster in 1986 — lacks the containment dome and protective structure that is typical of modern nuclear power stations.