More than one million copies of the book have been printed

Publisher Gallimard Jeunesse said it had printed one million copies of the book, which was published in English six months ago.

More than 250,000 copies have already been reserved in bookshops, they said.

The French editions has been on the top of Amazon France's bestseller list since pre-orders began in June.

Following its release in the summer, the English version of The Order of the Phoenix became the first English-language book to top the French book charts.

French translators of the book were only given copies when the book was released in June in order to prevent plot leaks.

Legal action

Four bookshops received official warnings that could lead to lawsuits, the publisher's sales director Bruno Caillet said.

On Monday, Gallimard Jeunesse said it had taken action against booksellers who had sold copies before the French launch.

Last month, representatives of author JK Rowling said the five books had sold more than 250 million copies around the world.

The first two books - The Philosopher's Stone and The Chamber of Secrets - have already been made into successful films, with Daniel Radcliffe playing the boy wizard.

The third, The Prisoner of Azkaban, is currently being filmed.