Characters such as Mad-Eyed Moody, evil Lord Voldemort and Harry himself could be used as examples to help children think about social issues, the study says.

It suggests that passages in the books in which Harry is treated badly by his aunt and uncle for not being “normal” are a valuable metaphor for the exclusion and mistreatment of disabled people by wider society.

Mad-Eyed Moody, Harry’s glass-eyed teacher, commands respect in spite of his physical disability, according to the study, presented to the American Educational Research Association conference last week.

Hermione Granger, portrayed as the cleverest pupil in school, despite the fact that she is not of “wizard blood”, can be used to challenge racist and sexist prejudices, says the researchers.

“Harry Potter can be used to examine the concept of stigma and acceptance and help children better understand the social structures of their own school communities,” said authors Heeral Mehta-Parekh and Maria Molnar of Columbia university.

They also pointed out that Lord Voldemort’s character fits a well-established literary stereotype which uses disability - in this case his lack of a body - to represent evil.

Teachers should encourage children to discuss why authors do this, the paper said.

To order a copy of Scratching the Surface: Using the Harry Potter series as a tool for teaching disability metaphors email: heeralparekh@yahoo.com