Harry Potter and the Deathly Hallows, the seventh and final volume in the Harry Potter series has become the fastest selling book in history, publishers say.

Almost 11.4 million copies were sold in three countries on the first day, according to figures released by its publishers.

US sales of the eagerly awaited Harry Potter and the Deathly Hallows hit 8.3 million, comfortably beating the previous Potter instalment, which posted sales of 6.9 million copies in the first day, US publisher Scholastic announced.

In Britain, Bloomsbury sold a record 2.7 million copies of the final Potter book in the first 24 hours, up from 2.0 million for Harry Potter and the Half-Blood Prince.

The same company also announced nearly 400,000 copies of the English language edition of JK Rowling's story were bought in Germany over the same period.

US publisher, Scholastic, said it printed a record 12 million copies in anticipation of the release on Saturday.

Thousands of Harry Potter fans queued outside book stores in major cities around the world over the weekend to get hold of the book, which answers the questions on every reader's lips - 'Who dies at the end?' and in particular, 'Does Harry survive?'

In India, police said on Monday they seized hundreds of pirated copies of the cover of Deathly Hallows after raiding a printing press, storage depot and private home in Bangalore.

Internet versions of the book also surfaced last week and two US newspapers ran reviews before publication, but it was not enough to dampen enthusiasm for the last chapter of the boy wizard's increasingly bloody fight against the forces of evil.

Lisa Holton, president of Scholastic Trade and Book Fairs, likened the weekend excitement in the United States to the hysteria that greeted the Beatles' first visit to the country.

"This weekend kids and adults alike are sitting on buses, in the park, on airplanes and in restaurants reading Harry Potter and the Deathly Hallows," she said in a statement.

Barnes & Noble Inc, the world's largest book retailer, sold 1.8 million copies of Harry Potter and the Deathly Hallows in the first 48 hours, while Borders Group Inc sold around 1.2 million worldwide in a single day, both records for the outlets.

"This isn't the end of Harry Potter by any means," said Steve Riggio, CEO of Barnes & Noble.

"Barnes & Noble expects to sell millions of Harry Potter books over the next few years."

Reviews of Harry Potter and the Deathly Hallows have been almost universally glowing, noting the darker tone of book seven in which several characters die. Critical reaction to the previous six Potter tales, which sold 325 million copies worldwide, has been mixed.

Rowling, 41, is likely to see her fortune swell further over the coming years. She is estimated to be worth 545 million pounds ($A1.27 billion) already, making her the first dollar-billionaire author.

In addition to the books, the first five Hollywood adaptations of her Harry Potter stories have amassed around $US4 billion ($A4.53 billion) at the global box office. The final film in the franchise is slated for release in 2010.

"After 608 crammed pages, it's still hard to believe it really is the end of the road for Harry Potter," said Henry Sutton, books editor for the Daily Mirror tabloid in Britain.

He believes that the epilogue at the end of book seven means there is "no possible return" for the Harry Potter saga, although not everyone agrees.

Hours after the release of Harry Potter and the Deathly Hallows, Ladbrokes bookmakers cut their odds on an eighth Harry Potter tale to 10/1 from 16/1, following a flurry of bets.