'Pottermore' a net-based game?

Harry Potter fans are holding their collective breath as author JK Rowling gets set to reveal her latest project involving the boy wizard.

Rowling has called a news conference on Thursday in London (9:00pm AEST) to reveal the details of "Pottermore", a mysterious website that has been taunting fans with the words "coming soon".

Theories include a Harry Potter encyclopaedia, ebook versions of the novels or an internet-based game.

Several British newspapers received what appeared to be a leaked marketing memo indicating that the site is a web-based game including a hunt for real magic wands. But Rowling spokeswoman Rebecca Salt said that the memo, dated December 2010, was "an out-of-date document that got sent out by mistake", and that true details of the project would be revealed on Thursday.

"Pottermore" was trademarked in 2009 by Warner Bros, which distributes the Potter movies, but Salt said that the site is not directly linked to the latest film, Harry Potter and the Deathly Hallows: Part 2, which has its world premiere in London on 7 July.

Rowling has not ruled out writing more books set in the Potter universe, but Salt has said that "Pottermore" is not a new book.

The trademark description suggests an interactive site "providing online chat rooms and electronic bulletin boards", and "online facilities for real-time interaction with other computer users concerning topics of general interest".

A leading Potter fan site, The Leaky Cauldron, said that it had seen a preview of Pottermore, and called it "breathtaking".

Another Potter fan site, Mugglenet, whose webmaster met Rowling in 2005 and interviewed her alongside the webmistress of The Leaky Cauldron, reported: "I saw a preview of Pottermore recently, and can tell you that it is fantastic. I'd say more but I had to make an unbreakable vow concerning its secrecy."

The Harry Potter books have sold around 450 million copies worldwide, and spawned a hit movie franchise and a theme park. Forbes magazine has ranked Rowling as one of the richest women in Britain, with an estimated wealth of $AU947.91 million ($US1 billion).