NEW YORK (AP) — The producer of the Broadway production of Harper Lee's "To Kill a Mockingbird" has filed a counter suit against the executor of the late author's estate, which has challenged screenwriter Aaron Sorkin's adaptation.

Scott Rudin's production company, Rudinplay, filed the lawsuit in Manhattan on Monday, demanding $10 million from Lee's estate for damages and threatening to cancel the play scheduled to open in December.

Lee's estate filed a federal lawsuit last month in Alabama over the play, arguing Sorkin's script wrongly alters Atticus Finch and other characters from the book.

Rudin claims the estate's lawsuit made it difficult to secure money needed to finance the production based on Lee's Pulitzer Prize winning novel.

Rudin insists the play is faithful to the novel and seeks to have the Alabama lawsuit dismissed.