Finland’s maritime monitoring system received 18,000 false signals about “ghost ships” in just one hour, according to the country’s transport and communications agency, Traficom, reports, Helsingin Sanomat newspaper.

But the actual locations of these ships were thousands of kilometers away from the signals reported by the system, which were shown in the Baltic Sea.

One Spanish ship en route from Somalia to Japan was mistakenly shown to be in the Gulf of Finland.

The cause of this disruption is unknown.

Traficom has not ruled out that the incident may be the result of deliberate interference with ship tracking systems.