The final book in the Harry Potter series was meant to be the most closely guarded secret in publishing history, protected by padlocks, barbed wire and a small army of lawyers.

But representatives of J. K. Rowling and her publisher were struggling to get the genie back in the bottle yesterday after every page of Harry Potter and the Deathly Hallowswas apparently leaked on the internet three days ahead of the official publication date.

Representatives of Rowling confirmed that some genuine material had been released online but declined to say whether the complete book was available.

One possible source of the leak is the 1,200 customers who were mistakenly sent copies of the book on Tuesday by an American distribution company. Scholastic, the book’s American publisher, announced last night that it was taking legal action against Levy Home Entertainment, a Chicago based distributor, and DeepDiscount. com, an online retailer, for allegedly breaching their sales agreements. It estimates that the early copies represent 0.01 per cent of its initial print run of 12 million.

The version available online appears to be the 759-page American edition. A photographer, who is unseen except for a hand holding the book open, has copied each page into a file which can be read like an electronic book. It contains 36 chapters and an epilogue purporting to explain the characters’ ultimate fate.

The document was available yesterday from file-sharing websites including the Pirate Bay, a Swedish site that habitually allows users to make copies of copyrighted material.

Neil Blair, Rowling’s lawyer at the Christopher Little Literary Agency, said that some apparently genuine pages had been posted on the internet. “There is a whole mix of stuff up there,” he said. “If we are alerted to anything that looks like it could be genuine, then we take action. There have been some photos of things up there that do appear to definitely come from the cover or the inside chapter title pages.”

Some file-sharing websites have removed the book after receiving legal warnings, but the Pirate Bay, which has a history of defying legal threats from aggrieved organisations such as Microsoft and Dreamworks, continued to distribute the file last night. It has been downloaded by more than 1,000 people.

If the text is genuine, it is the first time a complete version of the book has been made available online prior to publication. Previous leaks have consisted of selected pages and chapters.

Websites devoted to Harry Potter have appealed to fans not to reveal any leaks that would spoil the plot and are having to remove comments left by visitors who ignore the request.

Rowling has warned readers to expect at least two deaths, but the version online is a bloodbath, according to people who have read it.

The author has declined to comment, but previously asked that readers respected the embargo. “I want the readers who have, in many instances, grown up with Harry, to embark on the last adventure they will share with him without knowing where they are going,” she wrote on her website.

She described those who ruin others’ enjoyment as “sad individuals”.

Bloomsbury said that it hoped fans would be able to ignore temptation over the next two days.

Should you be downloading this book?

Anyone who downloads a copy of Harry Potter and the Deathly Hallows is breaking the law and may even be comitting a criminal offence, lawyers said last night.

Robin Fry, the head of intellectual property at Beachcroft, said that people who use file-sharing software to download the book are also unwittingly distributing it at the same time.

Peer-to-peer networks operate by obliging users to make available parts of the file that they have already downloaded to others on the network.

“Since the very act of downoading automatically means that the version you obtain is then also exposed to the rest of the world whilst your computer is running, any downloads could mean an injunction or criminal proceedings, not just for the originator but also each reader,” he said.

“There’s no doubt that given the fastidious requirements and huge marketing spend of this launch that anyone breaching the embargo – particularly via peer-to-peer networks – can expect not just civil proceedings but warrants being issued for search and arrest.”

The maximum sentence for breaching the Copyright, Designs and Patents Act (1988) is two years imprisonment or a £5,000 fine.

John Cooper, a criminal barrister, said that downloading and distributing the book was illegal, but in practice Bloomsbury, the publisher, would be likely to pursue only big offenders.

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