Rowling had hidden the title on her official website (www.jkrowling.com), and visitors to the site had to play an online game to find out what it was, Britain’s BBC news channel reported. US publisher Scholastic confirmed the title in a statement.

Rowling said in a posting on her website that she is still working on the eagerly anticipated finale of the series.

"I’m now writing scenes that have been planned, in some cases, for a dozen years or even more,’’ she wrote. "I don’t think anyone who has not been in a similar situation can possibly know how this feels: I am alternately elated and overwrought. I both want, and don’t want, to finish this book (don’t worry, I will.)’’

The author had already indicated that two characters would be killed off in the final book. She did not rule out that one of the two would be the lead character, Potter himself.

Harry Potter books have been translated into more than 60 languages and have sold more than 300 million copies around the world. The first four books have been made into films which have grossed more than 3.5 billion dollars at the box-office.

Forbes estimated Rowlings’ wealth at more than 1 billion dollars, making her the first person ever to become a billionaire from writing books.

No publication date was given for the final book, which details Potter’s last year at Hogwarts magic school.