Timothy Spall Cast For 'Harry Potter 3'?

Harry Potter and the Prisoner of Azkaban
AICN are reporting that Timothy Spall has been cast as Peter Pettigrew for Harry Potter and the Prisoner of Azkaban. Peter Pettigrew is also known as Wormtail in the Harry Potter books.

Warner Bros. have not yet confirmed this, so is currently all considered as rumor.