"On the night of December 28, many of Amedia's central computer systems were attacked by hackers. Online publications are issued as usual, but paper editions are not published on Wednesday," the media group said in a statement.
Systems responsible for publishing printed media, announcements and subscription plans do not work as intended, according to the statement. The company said it considers the situation to be serious and does not rule out the possibility that user data might have been accessed by hackers. However, it noted that the potential leak does not contain passwords or account data of subscribers.
The group's leadership intends to contact law enforcement agencies as part of an investigation into the incident.
Amedia publishes more than 90 newspapers and other printed products with an estimated audience of over two million people.