The Association of American Publishers estimates that half of the pirated books found by its members were linked to Rapidshare.

"There's a lot of money being made," said DeMarines. "Without hosting pirated goods, I'm not sure what their revenue model would be."

According to a recent investigation by V.I. Labs into the availability of pirated software from a sample of 43 vendors, 100% were on RapidShare.

A spokeswoman for Cham, Switzerland-based Rapidshare declined to comment on the V.I. Labs report, saying she would need more information.

The site is already among the top twenty most popular in the world, Uploads and downloads to Rapidshare account for 5% of all Internet traffic globally, says German networking vendor Ipoque.