The Ukrainian government and several public institutions, banks, major industrial enterprises, the postal service, and Kyiv's international airport have been hit by a series of cyberattacks.
Ukrainian Deputy Prime Minister Pavlo Rozenko said on Facebook on June 27 that every computer monitor in the cabinet of ministers was locked and displayed a message in English warning users that if they shut down their computers all of their data will be deleted.
Rozenko said on Twitter that "the entire network is down in the government's secretariat. It has either been hacked or shut down by the security system. That's unclear."
The Ukrainian central bank said a number of Ukrainian banks were also affected by the attack -- which it described as being caused by an "unknown virus."
"As a result of these cyberattacks these banks are having difficulties with client services and carrying out banking operations," it said in a statement, without naming any of the banks affected.
"The central bank is confident that the banking infrastructure's defense against cyberfraud is properly set up and attempted cyberattacks on banks' IT systems will be neutralized," the statement added.
Ukrainian state power distributor Ukrenergo said its IT system had been hit by a cyberattack on June 27, but the disruption had "no effect on power supplies."
Several local power distributors also experienced disruptions due to the cyberattack, including Kyivenergo, Dniproenergo, and Zaporizhiaenergo, Interfax-Ukraine reported.
Anotonov, the Ukrainian state-run aircraft manufacturer, has also been hit by a cyberattack. A spokeswoman for the company said it was still unclear how serious the attack is.
Also in the capital city, the Kyiv subway said on Twitter that its payment system had been hit by a cyberattack and credit-card payments were not being processed.