Computer networks of the Ukrainian government, Kyiv City Administration and dozens of major state-run and private banks and companies experienced a massive malware attack on Tuesday, and some have had to suspend operations.

"As a result of these cyber-attacks, the [affected] banks are experiencing problems with servicing their clients and conducting banking operations," the National Bank of Ukraine (NBU) told Kyiv's Interfax-Ukraine's inquiry.

The intelligence services told Interfax-Ukraine that specialists of the State Service of Special Communications and Information Protection and cyber-police are involved in the investigation of the cyber-attack.

The NBU warned banks and other financial market players of a hacker attack using an unknown virus at several Ukrainian banks and some commercial and public sector companies on Tuesday.

Director General of Lux television and radio broadcasting company (24 Channel) Roman Andriyko told Interfax-Ukraine that it was also affected by the cyber-attack.

"Some computers of the television channel and the radio station have been damaged. We use compact discs to broadcast," he said.

Nova Poshta also reported about the hacker attack by the Petya.A virus. Its information systems and the call center are experiencing difficulties with operations.

"We are doing our best to resume operations in the near term. Thanks for understanding. We promise to inform on the situation," the company said on its Facebook page.

"Important! Now most leading Ukrainian companies and banks are facing a cyber-attack, including our network. We apologize for possible failures in operations of the company," WOG, the fuel market player, said.

The Boryspil and Kyiv airports told Interfax-Ukraine about the damage to their internal computer networks. However, all air navigation systems are operating normally, planes depart and arrive without delay, the airports stressed.

The central office of PJSC Ukrgazvydobuvannia was also hit by the virus, head of its PR department Larysa Polischuk said. "Today, the networks of several banks are down and this is the evidence of a large-scale cyber attack in the country. Now all the computers of the Ukrgazvydobuvannia are off. We are working using our phones," she wrote on her Facebook page.

Oschadbank said that in compliance with the rules of security and information protection, they had to limit the services provided to clients. "The bank's offices will provide only consultations today, customers of Oschadbank can now use ATMs of other banking institutions," the bank said. At the same time, the "Oschad 24/7" web and mobile banking system is working as usual, and operations with credit cards are carried out normally.

Ukrlandfarming and Avangard companies, whose stocks are traded on the London Stock Exchange, also reported the hacking attack on their computer networks.

"The attack was carried out with the help of an unknown virus, which significantly limited efficiency of the company's computer systems," the press service told the agency. They noted that the IT departments are taking all the necessary measures to restore their systems operation and minimize losses for the enterprises of the holding, partners and customers.

Earlier, Kyivenergo and Ukrenergo said they were also attacked by the virus. However, Ukrenergo said the problems their computer systems encountered are not critical.

According to Interfax-Ukraine, Ukrposhta, Ukrtelecom, the KLO gas station network also fell victim to the virus.

At the same time, Energoatom and Naftogaz Ukrainy reported that they did not suffer as a result of hacker attacks.