Finland's maritime surveillance system registered 18 false signals regarding the location of alliance ships in one hour, the Helsingin Sanomat newspaper reported, citing the Transport and Communications Agency Traficom.

The fake markers appeared exclusively in the Baltic Sea, although the actual vessels were thousands of kilometers away from the indicated coordinates. One Spanish warship, en route from Somalia to Japan, was mistakenly placed in the Gulf of Finland.

The cause of the widespread outage remains unknown. Traficom does not rule out deliberate interference with the global Automatic Identification System (AIS).

"We do not deny that the incident could be the result of deliberate interference with ship tracking systems.", the publication quotes the agency's representative.

The disruption lasted about an hour and did not affect actual shipping. The investigation is ongoing.