Hackers targeted Ukraine's largest mobile-only bank, Monobank, with a powerful denial of service (DDoS) attack on May 2, the company's co-founder and CEO Oleh Horokhovskyi reported.
DDoS attacks direct excessive amounts of traffic at a website in order to overload its servers, often causing disruptions to service.
Horokhovskyi announced "another powerful DDoS attack" against the bank at around 1 p.m. local time.
The bank's CEO reported a similar attack earlier this year. The bank simultaneously received 580 million service requests.
Horokhovskyi did not say who he thought was behind the attacks, though previous threats have been linked to Russian hackers.
Russia has launched thousands of cyberattacks against Ukrainian organizations since the start of its full-scale invasion.