Ukraine's energy ministry is launching an investigation after a suspected cyber attack hit the country's power grid and caused outages during December.
Reuters reported at the end of December that Prykarpattyaoblenergo, a power company in western Ukraine, said that a large swathe of the area that it serves had been left without energy due to "interference" with its system. Other power companies in the region also reported problems.
In all, some 700 000 people in the Ivano-Frankivsk region were left without power for several hours. Ukraine's state security service, SBU, has blamed Russia for the attack, an allegation to which Moscow has yet to respond.
It is thought that the suspected attack is the first of its kind to succeed in shutting down a network. Power companies are known to be vulnerable to cyber attacks because of the critical infrastructure they operate.
According to cybersecurity firm ESET, the cyberattackers used the BlackEnergy backdoor trojan, which employs various downloadable components to carry out specific tasks.