In what promises to be one of the biggest publishing events in recent years, book stores and online retailers are bracing for another outbreak of Pottermania as fans across the world snap up copies of "Harry Potter and the Deathly Hallows."

Adding to Harry hype this summer will be the release just over a week earlier of "Harry Potter and the Order of the Phoenix," the fifth Hollywood blockbuster based on the books.

Wayne Winstone, children's manager at British bookseller Waterstone's, predicted the book would become the fastest selling of all time, a record currently held by the sixth installment, "Harry Potter and the Half-Blood Prince."

"For the bookselling industry, this is the most exciting day so far this year," said Winstone. "Harry Potter has built book by book into a global phenomenon," he told Reuters.

On the release of the sixth book in July 2005, thousands of young Potter fans queued for hours outside stores in Australia, India, Britain and the United States and reviews hit the Internet within hours of the first copies being bought.

Bloomsbury Publishing, which handles the Potter books in Britain, said on Thursday that the series had sold 325 million copies worldwide.

"It may be a long time before we see another book that commands as much anticipation, attention and demand as this final book," said Christopher North, head of books at the British arm of online retailer Amazon.

PLOT SPECULATION, PRICE WARS

Speculation has been rife that Rowling, who became the world's first billion-dollar author on the back of the success of the Harry Potter books and spin-off movies, may kill Harry off at the end of book seven.

She said last year that at least two characters would die in the final book, and that she understood authors' desire to kill off the main character of a successful series.

Two top U.S. writers, John Irving and Stephen King, were sufficiently concerned about the fictional hero's fate to urge Rowling to spare him.

Retailers fired the opening salvoes in what is likely to be an aggressive price war to ensure customers come to them to buy their Harry Potters.

Waterstone's will be offering the book, with a recommended retail price of 17.99 pounds ($35.40), for 8.99, while Amazon.co.uk lowered its price to 8.99 pounds from 9.99 earlier on Thursday and 13.99 pounds prior to Bloomsbury's announcement.

Experts say that prices may come down further still.

Independent book stores have complained that they cannot compete with reductions offered by the big chains, and so miss out on the financial benefits of the Potter craze.

Bloomsbury, which announced the publication date on Thursday, said it remained cautious about its outlook in light of challenging market conditions, but the announcement supported its previously stated view of a satisfactory outcome for 2007.

Its shares were trading at 224 pence at 1544 GMT on Thursday, up nearly two percent from Wednesday's close. Broader shares were also higher, with the FTSE 100 around 1.5 percent higher by the same time.