People who came through a humanitarian corridor use their mobile phones in a hall of a humanitarian center in Sumy, Ukraine, on the evening of Nov 8, 2023. (PHOTO / AFP)

KYIV - A massive cyber attack struck Ukraine's largest mobile phone operator Kyivstar on Tuesday, bringing down mobile communication and internet access across the country.

The Security Service of Ukraine said in a statement that it has opened criminal proceedings into the attack.

Russia's special services might be behind the attack, the Security Service of Ukraine said.

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Oleksandr Komarov, Kyivstar's president, said that the IT infrastructure of the company was partially destroyed by the attack, the Economichna Pravda media outlet reported.

According to various media reports, the attack disrupted the work of ATM machines and pos-terminals in Ukraine.

It also affected the operation of air raid alert systems in more than 75 settlements in the Kyiv region, the regional military administration said on Telegram.

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Kyivstar provides services to over 24 million mobile customers and more than 1 million home Internet customers in Ukraine.