Hackers from the Blackjack group, allegedly related to the Security Service of Ukraine (SBU), hacked the Moscow Internet provider M9com and demolished its servers, an informed source told Interfax-Ukraine on Tuesday.

"We are talking about 20 TB of deleted data: the company's official website, branch websites, mail server, cyber protection services, and so on. As a result, some Moscow residents were left without the Internet and television," the agency's interlocutor said.

Data from the company's mail server and client databases were also posted online. Hackers called the attack on M9com a "warm-up" as part of a retaliation campaign for a hacker attack on the servers of the Ukrainian mobile operator Kyivstar.