The publishers of CS Lewis's The Chronicles of Narnia plan to give the novels a Harry Potter makeover and to play down their Christian themes to attract new readers, claim academics.

They fear the fantasy kingdom of lions, dwarfs and errant English schoolchildren will become little more than a version of Mickey Mouse.

Encouraged by the success of Harry Potter, the Lewis estate and its publishers HarperCollins are reported to have struck deals to launch a series of toys and to create new Narnia novels. A leaked memo reportedly says: "We'll need to be able to give emphatic assurances that no attempt will be made to correlate the stories to Christian imagery/theology."

Academics claim Lewis would have been horrified. He was one of the 20th century's most influential interpreters of Christianity by mixing fantasy with Christian allegories.

The seven novel saga that began with The Lion, the Witch and the Wardrobe has sold more than 65m copies in more than 30 languages.

John West, co-editor of the CS Lewis Readers Encyclopedia, told the New York Times: "They're turning Narnia into a British version of Mickey Mouse."