Editor's note: This news item initially reported on a large-scale failure in Kyivstar's services. It was updated after the company announced that the outages were caused by a hacker attack.
The Ukrainian telecommunications company Kyivstar said on Dec. 12 that it came under a powerful hacker attack after subscribers complained about network and internet outages.
Kyivstar is Ukraine's leading phone services provider, with over 24 million mobile customers and more than 1 million Home Internet customers as of September this year.
The attack caused a large-scale technical failure that resulted in the loss of mobile connection and internet access "in parts of (Kyivstar's) subscriber base."
The company said its specialists are working on solving the problem with law enforcement and security services' involvement.
"The most important thing is that, as of now, the personal data of subscribers is not compromised. We sincerely apologize for the temporary inconvenience and thank you for your understanding," the company's announcement read.
"Yes, our enemies are treacherous. But we are ready to face any difficulties, overcome them, and continue to work for Ukrainians."
Users have been reporting problems since the morning of Dec. 12, saying they are unable to make or receive calls and use internet services.
Kyivstar's website has also been down since 9 a.m. local time.