Increasing sales of eReaders is good news for Amazon, which produces the best-selling Kindle and collects 30 percent of the price of downloaded books.
But profits could be hit by the sheer number of pirate eBooks available for free download. Just as pirates and websites, including Napster, undermined the music industry by putting music on the web for free, the same is now happening with eBooks.
An agreement among six major publishers, including Harper Collins and Penguin, also recently saw prices rocket for many eBooks - some of which are more expensive than the paper version.
Creating pirate copies of published books is simple and can be done using a computer and a scanner in a relatively short period of time, or by converting the file format of a 'bought' eBook, the Daily Mail reports.
Freely available software which people can download to their home computers is able to convert just about any document file for reading on a Kindle or other eReaders.
One pirate website boasts: "With Kindle, there is pretty much no protection against pirated books. There are programs which can simply convert any piece of text into the proper format and it will show on your Kindle as if you had bought it!"
It is estimated that up to 20 percent of eBook downloads are from pirate sites.
The Publishers Association issued 115,000 legal threats to websites to stop them offering free pirated books in 2011, a rise of 130 percent on 2010.
Publishers have asked Google to demote pirate websites to ensure they do not appear at the top of web searches for consumers looking to find eBooks. Pressure is also being put on internet service providers to shut down pirate websites.