The latest instalment of the Harry Potter wizarding saga has become by far the fastest-selling book in British history, with more than two million copies shifted in Britain in its first 24 hours on sale.

Harry Potter and the Half-Blood Prince, the sixth episode in JK Rowling's series, went on sale at one minute past midnight on Saturday and sold more in its first day than Dan Brown's bestselling The Da Vinci Code has sold in a year.

Bloomsbury, the book's UK publisher, said that total first day sales reached 2,009,574 copies through UK bookshops, supermarkets, websites and newspapers, according to Neilsen BookScan estimates.

Worldwide sales in the first 24 hours are expected easily to top 10 million sales. A spokeswoman said: "It has finally knocked The Da Vinci Code off the top spot."

At Asda, where a vicious price war among supermarkets saw the book selling for £7.96, more than 66,000 copies were snapped up in the first hour of sales. Tesco claimed 400,000 copies sold in the first 24 hours.

WHSmith, which opened 391 outlets across the country at midnight on Saturday, had received half a million pre-orders. It reported selling 13 copies per second in the first 24 hours, compared with a mere eight copies per second for 2003's Harry Potter and the Order of the Phoenix.

Meanwhile, online bookseller Amazon.com reported that customers had ordered more than 1.5 million copies around the world. Royal Mail drafted in 150 extra vehicles to ensure deliveries.

Sales of the adult edition - with its more subdued front cover designed to save face among older readers - accounted for a quarter of all sales.

In America, where the book is published by Scholastic, 6.9 million copies of the hardback sold in 24 hours. The figure smashed the previous record - held by the fifth episode in the series - by almost 40 per cent and Scholastic has already increased its print run from 10.8 million to 13.5 million copies.

In Germany, where the translation is not due to appear until October - a shipment of 100,000 English-language copies were immediately snapped up by bi-lingual youngsters.

Within hours, the internet was buzzing with reviews - mostly positive - from readers all over the globe. A reader Buenos Aires in Argentina wrote on the Amazon website: "I literally battled rain and cold weather with my sister to get our copies at 12.15 am in a local bookstore in Argentina. According to my dad, I'm slightly nuts for doing that.



"After picking it up, I returned to my house and started to read it. I just finished it, and I can sincerely said that it is simply outstandingly good. And now, after staying up all night in order to read this book, I really need to catch up on my sleep..."

W Kennedy, posting from Florida, wrote: "I got it Saturday morning and finished it Sunday night. I laughed, I rejoiced, and I cried at the end."

In India, Bhushan Nigale, was entranced: "The hallmark of great fiction is to be able to sharpen the irony evident in the oxymoron: believable fiction. Great fiction creates a new World, a world that is largely entirely unconnected, often comparatively surreal, to the one we inhabit, and yet stunningly real when interpreted and imagined."

The first print run of Harry Potter and the Philosopher’s Stone, the original 1997 adventure, was 2,000. Before Friday, the series had recorded global sales of 270 million.

In her only interview to mark the launch of the book, billionaire JK Rowling, 39, said that she was taking six months' off before writing the final instalment to spend with her baby daughter Mackenzie Jean.

Readers have been warned to expect a two-year wait - and unprecedented levels of hype - before their final fix of Potter magic.

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