Internet pirates first attacked the music industry, then Hollywood film studios, undermining successively sales of CDs and DVDs by making available free downloads of songs and films. Now they have turned their attention to the books industry by pirating copyrighted text worth millions of pounds.

The result is that within months of ebook devices such as the Sony Reader and its rival, Amazon’s Kindle 2, taking off in the shops, everything from Harry Potter novels to Jamie Oliver cookbooks can be illegally downloaded from filesharing sites. Publishers are warning that they could suffer the same fate as the music business, which saw profits collapse overnight as programmes such as Napster and Kazaa gave users free access to copyrighted material.

The number of ebooks being uploaded by pirates is expected to rise from just over 1,000 last year to more than 5,000 this year. Since February alone, the Publishers Association has sent out 800 notices on behalf of its members ordering copyrighted material to be taken down. Despite its best efforts, sites such as the Pirate Bay, btjunkie and RapidShare, still offer users complete PDFs of bestselling novels from the likes of Stephen King and Zadie Smith at the click of a mouse.

Simon Juden, chief executive of the Publishers Association, says piracy poses the single biggest threat to the ebooks industry. Last year sales of ebooks represented less than 0.1% of the total UK books market. The American market is already worth an estimated $100m, and with sales set to rise in Europe, publishers are keen to avoid the mistakes made by the music industry.

George Walkley, head of digital products at Hachette, the publisher, says: “This is not a victimless crime. The first — and most important — thing we are doing is trying to ensure a broad range of our products is available through legitimate sources like Waterstone’s. The evidence from the music industry is that if people have an easy way to get hold of these things, it will discourage piracy in the first place.”

Fionnuala Duggan, digital director at Random House, said it was important for readers to have the freedom to lend to and borrow novels from friends and swap books between devices — for example, between a Sony Reader and an iPhone. That would mean some publishers relaxing restrictions that prevent files being shared.

DSB, a self-styled group of internet pirates that took credit for leaking Harry Potter and the Deathly Hallows before its release date, said its actions were justified because people would still pay for their favourite books regardless of their availability on free websites. The Pirate Party, a single-issue political group in Sweden, goes further and advocates widespread piracy of all types of material, arguing that the internet should become “the biggest library ever created”.

Explore Personal Tech

• InGear