An undersea fibre optic cable between Latvia and Sweden was damaged on Sunday, likely as a result of external influence, Latvia said, triggering an investigation by local and NATO maritime forces in the Baltic Sea.

"We have determined that there is most likely external damage and that it is significant," Latvian Prime Minister Evika Silina told reporters following an extraordinary government meeting.

Latvia is coordinating with NATO and the countries of the Baltic Sea region to clarify the circumstances, she said separately in a post on X.

Latvia's navy earlier on Sunday said it had dispatched a patrol boat to inspect a ship and that two other vessels were also subject to investigation.