Seventeen shipping container terminals run by APM Terminals have been hacked, including two in Rotterdam and 15 in other parts of the world, Dutch broadcaster RTV Rijnmond reported on Wednesday.
APM Terminals is a subsidiary of shipping giant Maersk , which has confirmed it is suffering from a cyber attack.
APM's website was difficult to reach and phones at its headquarters in The Hague and offices in Rotterdam went unanswered.
A spokeswoman for the company in Copenhagen confirmed its systems were "impacted" as part of Maersk's IT infrastructure.
The RTV report said computers were infected by ransomware that encrypted their hard drives. The broadcaster published an image of the screen of an affected machine with a message demanding a $300 payment.
(Reporting by Toby Sterling; Additional reporting by Jonathan Saul)