An estimated four million people were expected to gather at more than 5 000 bookstores across the country that have planned midnight launch parties to grab an early ride on the Potter retail juggernaut.

"We're prepared for this because we've been through it before," said Laura Porco, merchandising manager for books at Amazon.com, the online retail giant that, as of Thursday, had received nearly 900 000 US pre-orders for 'Harry Potter and the Half Blood Prince'.

The figure broke the record of 789 000 advance requests Amazon received for the last Potter book 'Harry Potter and the Order of the Phoenix' which was released in June 2003.

Appetite for the latest book was whetted by Rowling's revelation that a major character would meet his or her demise, and the US publisher of the Potter series, Scholastic Inc., responded to the demand with a record-breaking first printing of 10.8 million copies.

"The Harry Potter phenomenon is bigger than ever," Scholastic executive vice president Barbara Marcus said ahead of what the publishing house is touting as the biggest book launch in history.

The hype has been matched by the extraordinary security measures taken to prevent any copies of the book leaking out before the official release date and hour.

Scholastic requires the managers of the stores and libraries with which it deals to sign affidavits pledging to keep the copies under wraps and in a secure room.

In Amazon's main distribution centers, the books have been kept in restricted areas under the watchful eye of security guards, while the first signed copy arrived in New York under luxury lock and key aboard the transatlantic liner Queen Mary 2.

Inevitably, however, some lapses have occurred.

Nine-year-old Sylum Mastropaolo could hardly believe his luck when his mother returned from a shopping trip on Monday with a copy of 'Harry Potter and the Half-Blood Prince' that she had bought at a small drugstore in upstate New York.

The drugstore owned up to what it insisted was an honest mistake, and Sylum, in a stirring display of restraint, returned the book after reading only two pages.

A Canadian supermarket chain accidentally sold 14 copies after putting the book on its shelves a week before the real launch.

Amid reports that Pope Benedict XVI has concerns over the corruptive influence of Rowling's books on children, US conservationists have latched onto the latest Potter launch to push a more secular agenda — recycling.

Several environmental groups, including Greenpeace, have called for US Potter fans to boycott the Scholastic edition in favour of the Canadian edition which is printed on 100 percent recycled paper.

And blind followers of Harry and his pals at Hogwarts School of Witchcraft and Wizardry won't have to wait until late in the term to get their fill of the latest Potter adventure.

For the first time, Scholastic provided the Boston-based National Braille Press with an advance copy. Nearly 50 employees at the specialist publisher have been working overtime for the last two weeks to get 800 braille editions ready for distribution just three days after the main launch.

A giant video screen in New York's Times Square will count down the final hours and minutes to today's midnight release, ticking in synch with 40 000 'Harry Potter and the Half Blood Prince' countdown clock standees that Scholastic shipped to retailers nationwide.

The stores organising midnight parties are offering live owls, wand making classes and magic potion demonstrations as they vie to draw the largest number of early buyers.

Ans as newspapers struggled for new angles on the Potter story, the Boston Globe located a 50-year-old funeral director whose real name is Harry Potter.

"Sometimes, while making funeral arrangements, I'll hear: 'I'm going to tell my granddaughter I just sat with Harry Potter'," Potter said.