The world's biggest record labels first sued Napster in December 1999, claiming it was a haven for copyright piracy that would cost them billions of dollars in lost music sales. "Since we began blocking certain files, we have been progressively refining the system to both more accurately and more thoroughly block access to music files we have been asked to exclude," Napster said in a message posted on its Web site. A spokesman for the Recording Industry Association of America said: "We're pleased that Napster is announcing more and more steps toward compliance with the injunction."