Police in Germany are investigating after the Funke Media Group said on Wednesday it had fallen victim to a nationwide cyber-attack, including on its editorial offices and printing houses.
The publisher said several of its central IT systems had been hit in an attack on Tuesday, which affected all of its main locations in Bavaria, Berlin, Hamburg, Lower Saxony, North Rhine-Westphalia, and Thuringia.
Police in the western cities of Cologne and Essen have opened investigations into the incident, with specialist state police also involved, while the extent of the attack is unknown.
"The perpetrators encrypted data on the IT systems of the Funke Media Group," the company said in a statement.
Local media said that the attack on Funke Media Group resulted in staff being unable to log into its internal systems and access their email accounts.
Some reports suggested it was likely that the hack involved ransomware, in which hackers send phishing emails with attachments containing malicious code that are then unwittingly downloaded by employees.
The code then spreads through a company's systems, which hackers can then encrypt, allowing them to demand ransoms for the release of the data.
The Essen-based publisher apologized to its 3.3 million readers for the disruption, adding that it has waived paywall charges so people can access its 'e-papers' and download them for free.
The company said it was working "flat out" to address the problems, and announced it has set up a "task force" with internal and external IT and forensics experts who are investigating the incident.
It has also filed criminal charges and reported the breach of its systems to the data protection authorities.
Funke Media Group owns Germany's second most-read newspaper, Berliner Morgenpost, as well as dozens of regional titles.