Harry Potter and the Half-Blood Prince is already battling Transformers: Revenge of the Fallen at the box office - the new wizard movie is outselling the robot action picture a week before it is released.

Advance sales of Harry Potter have rocketed in the last few days, with cinema companies predicting the film is on course to oust Transformers as the year's fastest selling movie.

The Transformers sequel is currently sitting on top of the American movie charts and has become the biggest film of the year globally, grossing a staggering $600 million in just 12 days.

But the robots' crown could soon be snatched away by Daniel Radcliffe's Potter - with the sixth movie in the magical franchise accounting for 65 per cent of all online tickets sold in the week before its release.

Rick Butler, head of online ticket company Fandango, tells the Hollywood Reporter, "The Half-Blood Prince is turning out to be one of our fastest-selling titles of the year."

Harry Potter and the Half-Blood Prince opens on July 15.

Harry Potter and the Half-Blood Prince Gallery

Images © Warner Bros.

(This news article provided by World Entertainment News Network)