Medowie Christian School has defended a decision to ban witches and warlocks from its annual book week parade and the Harry Potter series from the school library.

The school was one of many in the Hunter Valley that marked Book Week this week by asking children to dress up as their favourite book character for a parade.

Banned ... Harry Potter. Credit:AFP

Principal Samantha Van de Mortel asked parents not to send children to school on Wednesday as witches and warlocks because it was inconsistent with school values.

She said it was a standing policy because the school felt it was not in line with its Christian ethos.