"I will confirm that an investigation into what material is on the computers is under way," Cmdr. Bill Spann, an academy spokesman, said Monday. But he would not give any other details on the investigation.
Punishment for illegally possessing copyrighted material ranges from restrictions such as loss of leave to expulsion from the academy, Spann said.
The raid on dormitory rooms took place Thursday while midshipmen were in class, according to The (Annapolis) Capital, which first reported the seizure of computers on Saturday.
Each of the 4,000 midshipmen is issued a computer upon entering the academy. The cost is deducted from midshipmen's monthly paychecks over the four years they are in school.
Amanda Collins, a spokeswoman for the Recording Industry Association of America, said entertainment industry and educational associations have sent two letters to colleges and universities around the country, asking them to address Internet piracy and establish policies against it.
An Oct. 3 letter from groups representing the motion picture and music industries asked college presidents to monitor use of student computers.
The recording industry estimates that more than 2.6 billion music files are downloaded illegally each month, usually through unlicensed services.
CD sales fell more than 5 percent in 2001 and dipped another 1 percent in the first half of this year, according to the RIAA.