According to MPK, the attack occurred early on Tuesday morning, disrupting public transport ticketing systems and online platforms.
"Information obtained indicates that this is an international hacker group carrying out commissioned attacks on enterprises," MPK said in a statement.
"Due to the scale and nature of the cyberattack," MPK said it reported the incident to the police and state cybersecurity agencies.
The company also notified the Office for Personal Data Protection about the potential risk of personal data theft involving employees and passengers.
"Currently, there is no confirmation that such a theft has occurred; however, we decided to inform all concerned parties about this risk," the statement said.
MPK urged customers, partners and employees to be vigilant against unusual emails, phone calls or contact attempts and recommended securing their personal identification numbers.
"The method and scale of the hacker attack indicate that the main goal was to paralyze the operations of Krakow's public transport," MPK said, adding that it has "implemented procedures designed for such situations" and maintains "uninterrupted operation of depots and service stations."
"MPK continues to provide transport services in full," the statement also said.
(jh/gs)
Source: PAP