JK Rowling has publicly lambasted US newspapers that have published plot details from the final Harry Potter book, Harry Potter and the Deathly Hallows.

The author said she was "staggered" that papers including The New York Times had printed reviews ahead of the novel's official publication date of July 21 and said their disclosures were in "complete disregard of the wishes of literally millions of readers".

Rowling said the US newspaper reviews would particularly affect children "who wanted to reach Harry's final destination by themselves, in their own time".

"I am incredibly grateful to all those newspapers, booksellers and others who have chosen not to attempt to spoil Harry's last adventure for fans," she said in a statement.

The statement follows an earlier message on her website, in which she said: "Let's all, please, ignore the misinformation popping up on the web and in the press.

"I'd like to ask everyone who calls themselves a Harry Potter fan to help preserve the secrecy of the plot for all those who are looking forward to reading the book at the same time on publication day. In a very short time you will know everything!"

The book's UK publisher, Bloomsbury, said spoilers remained "unauthenticated" although it is understood that some books have distributed ahead of the publication date in the US.

The novel has also appeared on auction site eBay, while pictures of what appeared to be pages from the new book have appeared on the internet.

On Wednesday, the Baltimore Sun printed a review of the book, saying it had obtained a copy from a relative of one of its reporters who had received it prematurely.

New York Times journalist Michiko Kakutani claims she bought the book from a retail outlet in New York City before writing a review in the New York Times giving away the book's plot.

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