A casting call is to be held to find a girl to star in JK Rowling's Harry Potter spin-off film-"Fantastic Beasts and Where to Find Them". [Photo: comicyu.com]

An open casting call is to be held to find a girl to star in JK Rowling's Harry Potter spin-off film-"Fantastic Beasts and Where to Find Them".

Film studio Warner Bros is looking for a girl between the ages of eight and twelve to play a character called "Modesty".

The chosen youngster will star opposite Eddie Redmayne in what is bound to be one of the biggest film releases of next year.

Redmayne will play a "magizoologist", who writes a Hogwarts School textbook about the weird and wonderful creatures he encounters.

Rowling has written the screenplay for the film, which is based on a Harry Potter spin-off book she published in 2001.

JK Rowling says "Fantastic Beasts and Where to Find Them" is neither a prequel nor a sequel to the Harry Potter series, but an extension of the wizarding world.

The movie is expected to be released next November.