The cast of JK Rowling's much-anticipated Harry Potter stage play has been revealed - and it's not what the fans expected.

Pottermore confirmed this morning that Jamie Parker, Noma Dumezweni and Paul Thornley will play Harry, Hermione and Ron in the two-part play which opens in London's Palace Theatre next summer.

JK Rowling told Pottermore: "I'm so excited with the choice of casting for Harry Potter and the Cursed Child. I can't wait to see Jamie, Noma and Paul bring the adult Harry, Hermione and Ron to life on stage next summer."

However, the decision to cast Dumezweni, an actress of South African heritage has caused a debate on social media.

Emma Watson played Hermione in the Harry Potter films alongside Rupert Grint and Daniel Radcliffe.

However, other Twiter users were quick to point out that Hermione's ethnicity is never specified in the Harry Potter books.

Harry Potter and the Cursed Child by Jack Thorne is based on a new and original story by J.K. Rowling, Jack Thorne, and John Tiffany.

The two-part play, which is a sequel to the Harry Potter books, will tell the "untold part" of the boy wizard's story, including the story of the lives of his murdered parents.

Previews for the play begin at London's Palace Theatre on June 7 2016.