Seven midshipmen have been expelled from the U.S. Naval Academy for using "spice," a form of synthetic marijuana, the Baltimore Sun reports.

An academy spokesman told the newspaper that sophomores and juniors were expelled for violating the Navy's illicit-substance policies.

The Department of Defense and the Navy consider spice, also commonly known as K2, a banned substance.

Officials learned of allegations about the use of spice last fall.

The Drug Enforcement Administration has moved to criminalize synthetic marijuana and says spice and similar products "consist of plant material that has been coated with research chemicals that mimic THC, the active ingredient in marijuana."