Russian forces damaged a high-voltage power connection to Ukraine’s Chernobyl nuclear reactor not long after electricity supplies were restored, grid operator Ukrenergo said in a statement on Monday.

It did not specify whether the plant’s external power supply had been disrupted as a result of the damage, but it wanted access to the region to make repairs.

Ukrenergo failed to give documentation of the damage or Russian forces’ operations, and Reuters was unable to independently verify the amount or cause of the damage.

Soon after invading Ukraine on February 24, Russian forces took the factory.