"This should not come as a surprise to anyone. Filing information subpoenas is exactly what we said we'd do a couple of weeks ago when we announced that we were gathering evidence to file lawsuits," said a spokeswoman for the RIAA, the music recording industry's leading trade body.

In late June, the RIAA announced that it would not only target peer-to-peer sharing services, but also its heaviest users.

Under the Digital Millennium Copyright Act, ISPs are required to provide copyright holders with such information when there is a good-faith reason to believe their copyrights are being infringed, according to lawyers for the RIAA.

Several hundred lawsuits are expected to be filed this summer.

Due to the recent court ruling in which Verizon was forced to reveal information about one of its users to the trade group, the RIAA intends to use this win under its belt. On June 4, the U.S Court of Appeals in Washington declined to suspend the order, allowing RIAA investigators to easily obtain the names of other Internet users it suspects of trading music illegally.

David Blumenthal, a spokesman for Earthlink, said the company had received three subpoenas in recent weeks asking the company to identify individuals.

"It is our intention to do so, based on the ruling on June 4," said Blumenthal. But, he added, "we disagree with the method that is being used here and while we support the right of them to enforce copyrights, we think this is the wrong method for doing so."

"We're urging the RIAA and other copyright holders to find a less intrusive method for protecting their intellectual property," he said.