An international alliance of publishers, including seven member companies of the Association of American Publishers (AAP), took legal action against the operators of www.library.nu and www.ifile.it this week.
The sites were served court orders in Ireland, where they were located after a seven month identification and enforcement process as part of an eBook anti-piracy drive.
A total of 17 plaintiff publishing companies filed requests for injunctions covering 170 book titles before a regional court of Munich, Germany.
The publishers alleged that Library.nu "illegally acquired more than 400,000 copyrighted e-books and made them available for free, anonymous downloading on a site that disguised itself as a legitimate provider and alluded to serving as an authorised library for such content".
They say that the site made an estimated €8m annually ($10,602,400), mainly through selling advertising space to third parties, but also through donations to the "internet library" through online payment services.
It is alleged that the same operators, who apparently "went to great measures to conceal their identities and locations", also ran the affiliated fileshare hosting service ifile.it, which "facilitated the anonymous, massive infringing uploads; these were downloaded through links made available on www.library.nu".
Despite the success of the enforcement action, AAP president and chief executive Tom Allen noted that this shows the lengths publishers must go to to protect their copyright.
"While this action is a significant step in shutting down two major rogue websites stealing content from publishers and others, it also captures the enormous investment of time and cost required for rights-holders to protect their work," he said.
"For every rogue site that is taken down, there are hundreds more demanding similar effort. I can't think of a more timely example of the need for additional tools to expedite such action."
AAP member publishing companies that participated in the action include Cengage Learning, Elsevier, HarperCollins, John Wiley & Sons, The McGraw-Hill Companies, Oxford University Press and Pearson Education Inc.
This comes as part of a worldwide crackdown on websites accused of piracy, including the high-profile closure of the Megaupload website last month by US authorities, and the arrest of its founders, including Kim Dotcom.
This week, music website RnBXclusive.com was shut down by the UK's Serious Organised Crime Agency (SOCA) over claims that it facilitated illegal filesharing that cost the music industry £15m a year.