WASHINGTON, May 12 (UPI) -- The number of terrorism and national security cases initiated by the U.S. Justice Department has declined by more than 50 percent, a recent study shows.

The non-profit Transactional Records Access Clearinghouse at Syracuse University says data it obtained from the government reveal a drop of 19 percent last year and more than 50 percent since 2002, the Los Angeles Times reported Monday.

The decline comes at the same time as the number of Americans being secretly wiretapped or having their financial records reviewed by the government continues to increase, the newspaper report said.

Civil liberties groups charge the government is compromising the rights of ordinary citizens without much to show for it.

"The number of Americans being investigated dwarfs any legitimate number of actual terrorism prosecutions and that is extremely troubling," Lisa Graves, deputy director of the Center for National Security Studies, a Washington civil liberties group, said to The Times.