VANCOUVER, British Columbia (Reuters) -- Harry Potter's latest secret has slipped out in Canada, and publishers of the best-selling books hope the magical allure of author J.K. Rowling's autograph will get it back under wraps.

Rowling's sixth book about the young wizard is scheduled to be released July 16, but a store near Vancouver briefly put the put the book on sale last week.

Raincoast Books Ltd., which distributes the books in Canada, said a "small number" of the books were sold, and it has won a court injunction barring the buyers of "Harry Potter and the Half-Blood Prince" from disclosing the plot.

The court also ordered all the copies be returned to Raincoast, which has promised the early buyers book plates autographed by Rowling once the embargo is lifted.