The Department of Defense (DOD) has indefinitely banned employees from using flash drives and confiscated all such devices issued to them after a virus was accidentally released its computer network.

The ban was issued last week after a Navy staff lost classified information from his computer after inserting a flash drive infected with a global virus or worm. An unnamed Navy rear admiral on Thursday described the virus as a worm, which is spreading rapidly in military computer networks.

"We have detected a global virus for which there has been alerts, and we have seen some of this on our networks," a Pentagon official told FOX News. "We are now taking steps to mitigate the virus."

The official declined to identify the attacker because the information is classified.