olish intelligence services are investigating a hacking attack on the country's railways, Polish media say.
Hackers broke into railway frequencies to disrupt traffic in the north-west of the country overnight, the Polish Press Agency (PAP) reported on Saturday.
The signals were interspersed with recording of Russia's national anthem and a speech by President Vladimir Putin, the report says.
The security breach took place when cybercriminals successfully breached the IT systems of a contractor in charge of producing warrant cards and staff passes.
