Within 24 hours of publishers announcing its release date, 30,000 advance orders had been placed with online bookseller Amazon.co.uk.

Harry Potter and the Order of the Phoenix, JK Rowling's fifth Potter story, is published on 21 June.

It is being tipped to beat record advance orders of 65,000 achieved by the previous Potter adventure, the Goblet of Fire.

Rowling's latest story could be another record-breaker

That became the fastest-selling book in history on the first weekend of its publication in July 2000.

More than a third of a million copies were sold on its first day of release as Potter mania swept the UK.

Amazon said the forthcoming book soared to the top of its chart within two hours of it becoming available.

Titles

Barnes and Noble, the world's largest book seller, said its US stores would remain open late on the night of Friday 20 June to sell the book at midnight.

All five Potter books - including previous titles the Philosopher's Stone, the Chamber of Secrets and the Prisoner of Azkaban - are still on bestseller lists around the world.

The Order of the Phoenix is being released on a Saturday - allowing thousands of young fans to buy it without taking time off school.

The fifth volume of the Potter series will be 38 chapters and 255,000 words - a third longer than the last book.

The official UK book chart is compiled by Nielsen BookScan, which analyses actual sales at more than 6,000 UK outlets.