The New York Times and the Baltimore Sun published reviews of the final Harry Potter book on Thursday before it went on sale, drawing a stinging response from author J.K. Rowling.
The New York Times review, which appeared overnight, said its copy was purchased from a New York City store on Wednesday, while the Baltimore Sun said it obtained a hard copy of the book through legal and ordinary means.
The official release of the eagerly awaited Harry Potter and the Deathly Hallows is not until 0001 British Summer Time on Saturday or 2301 GMT on Friday night.
Rowling, whose first six Potter books have sold 325 million copies worldwide, responded with a terse statement.
I am staggered that some American newspapers have decided to publish purported spoilers in the form of reviews in complete disregard of the wishes of literally millions of readers, particularly children, she said.
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, the 41-year-old added.
Bloomsbury, which publishes Harry Potter in Britain, and Scholastic, its U.S. counterpart, spent millions of dollars trying to protect the contents of the novel until publication.
But photographed pages from Deathly Hallows, believed to include both fake and real versions, surfaced on the Internet and this week some books were shipped to customers by a U.S. online retailer, prompting Scholastic to take legal action.
Publishing experts expect the seventh and final Harry Potter installment to become the fastest selling book ever after months of hype and speculation about its contents, including what happens to Potter and his friends at Hogwarts.
A Bloomsbury spokeswoman called the New York Times review very sad, adding that there was only one day to wait until the official release in book stores around the world. Twelve million copies of the book have been printed for the U.S. market alone.
She likened the events in the United States to the Boston Tea Party, a 1773 protest by American colonists against Britain.
But over here it is blockades as usual, with the embargo being enforced unflinchingly and without exception by all our customers, she said.
New York Times book editor Rick Lyman defended the newspaper's decision to run its review before publication.
Our feeling is that once a book is offered up for sale at any public, retail outlet, and we purchase a copy legally and openly, we are free to review it, a spokeswoman said.
We came across a copy of 'Harry Potter and the Deathly Hallows' at a store in New York City and we bought it.
We took great care not to give away the ending, nor to give away significant details about who lives and who dies, confining our review -- which, incidentally, had extremely high praise for both this final book and the entire series -- to broader-brush assessments of the tone and the writing.
In the review, writer Michiko Kakutani gives away some plot details, including roughly how many characters die and what deathly hallows means, but does not leak the big secrets.
Ms. Rowling has fitted together the jigsaw-puzzle pieces of this long undertaking with Dickensian ingenuity and ardor, the review said.
(Additional reporting by Andrew Marshall in Dubai)