"As a result, 144.9 MW load capacity of PJSC Kyivenergo and 58 MW load capacity of PJSC Kyivoblenergo were de-energized. Also, Kyiv pump storage power plant was de-energized with the loss of power for its own needs," the report says.

It is noted that the normal operation was restored one hour after the energy breach.

Hacking, as well as equipment failure (system crash), is considered as one of the possible causes of disruption.

Investigation into the causes of failure is underway.

Read alsoUkraine security chief calls for better cyber defense against Russia"Before the end of the official investigation into the case, the managament of all Ukrenergo facilities which have automatic control systems was downgraded to a local level," the company said.

Read alsoUkrzaliznytsya website hacked by Ukrainian hackers on order from Russia – Infrastructure MinisterIn turn, Ukrenergo Acting CEO Vsevolod Kovalchuk wrote on Facebook that as a result of this failure, consumers of northern part of the right bank of Kyiv and surrounding areas of Kyiv region were left without electricity at midnight.