The Recording Industry Association of America (RIAA) is expanding its legal efforts to curb online music piracy.

It plans a new wave of lawsuits and lawsuit-notification letters to users whom the RIAA alleges have illegally distributed significant amounts of copyright-protected music files online.

The group is filing 41 new lawsuits and sending 90 lawsuit-notification letters this week, adding to the 341 lawsuits filed and 308 notification letters sent since September.

The RIAA has settled with 220 file-sharers as a result of lawsuits, lawsuit-notification letters and subpoenas. In addition, 1,054 users have submitted affidavits as part of the RIAA's amnesty program.

Recent surveys have shown that the RIAA's campaign to seek legal punishment against individual music pirates is increasing awareness about the issue and prompting users to stop downloading music files illegally.

However, its campaign has also drawn criticism, particularly its attempts to force Internet service providers (ISPs) to disclose personal information about subscribers suspected of being illegal downloaders.

For example, SBC Communications and the American Civil Liberties Union are separately challenging the RIAA in court over this issue. The RIAA fought over this issue with Verizon Internet Services earlier this year, but won a favourable court decision that forced the ISP to turn over the personal information of subscribers.