LOS ANGELES -- An Internet tracking firm says file-sharing services saw a big dip in traffic the week after the music industry threatened to sue online music swappers.

According to Nielsen/NetRatings, two popular file-swapping services, Kazaa and Morpheus, had 15 percent fewer users during the week ending July 6.

SURVEY Are you personally worried about being sued by the Recording Industry Assocation of America? Yes, I've got a lot of illegal files. Yes, but I don't know how scared to be. Yes, but just a little. No, they're not likely to find me or my music. No, I don't have what they're looking for. Results  |  Disclaimer

The decline translates to about 1 million fewer users on Kazaa. About 41,000 fewer users signed on to Morpheus and the iMesh file-sharing service that week.

The Recording Industry Association of America announced last month it would soon begin suing individuals engaging in online music file-swapping. It has also warned corporations not to allow employees to trade files over their networks, and gone after students who set up trading sites.

The industry blames music downloading and CD burning for lagging sales in recent years.