Swedish authorities say they have called off their weeklong search for a suspected submarine in the Stockholm archipelago.

Military authorities said Friday that they have ordered naval and amphibious forces to end their hunt for the submarine, though some ground forces will remain involved.

Sweden's military launched its biggest anti-submarine operation since the twilight of the Soviet Union last Friday after receiving credible reports of foreign underwater activity in the archipelago that extends from the capital, Stockholm, into the Baltic Sea.

Military officials haven't blamed any country for the suspected intrusion, though most Swedish defense analysts say Russia would be a likely culprit.