Pope Benedict XVI thinks the best-selling Harry Potter series of fantasy novels about a boy wizard may undermine children's religious development by blurring the line between good and evil, according to comments attributed to him by a German sociologist.

Gabriele Kuby, a fervent Catholic who has written a book called 'Harry Potter - Good or Evil', says on her website that the pope, then Cardinal Josef Ratzinger, wrote to her in March 2003 to thank her for sending her "instructive book".

Extracts of the letter published on the website read: "It is good that you shed light and inform us on the Harry Potter matter, for these are subtle seductions that are barely noticeable and precisely because of that deeply affect (children) and corrupt the Christian faith in souls even before it could properly grow and mature."

Ratzinger fears that young minds will "lose the spirit of discernment between good and evil and that they will not have the necessary strength and knowledge to withstand the temptations to do evil."

Three hundred million copies have been sold in the Harry Potter series around the world so far. The sixth installment, 'Harry Potter and the Half-Blood Prince', hits bookstores overnight Friday.

AFP