Harper Lee's estate sues to block Aaron Sorkin's Broadway adaptation of 'To Kill a Mockingbird'
Author Harper Lee (AFP/Chip Somodevilla)

Screenwriter Aaron Sorkin's Broadway adaptation of Harper Lee's "To Kill a Mockingbird" is facing a legal challenge by the late author's estate over claims it dramatically rewrites the main character, Atticus Finch.

Lee, who died in February 2016 aged 89, agreed in 2015 to give producer Scott Rudin the rights to the theatrical production of the novel, one of the most popular works of American fiction.

Published in 1960, the book has sold more than 40 million copies, been translated in more than 40 languages and continues to sell about a million copies a year, according to a legal filing entered Tuesday before an Alabama court and seen by AFP Thursday.

"To Kill A Mockingbird" was previously adapted for the big screen in 1962, winning three Oscars, and was first produced for the stage by Christopher Sergel in 1970.

Lee's heirs grew worried by interviews given by Sorkin, an acclaimed screenwriter in his own right best known for "The West Wing" and "The Social Network," and sought a draft of the script.

Their main concern was over the portrayal of the novel's beloved main character, the crusading lawyer Atticus Finch.

Rudin attempted to reassure the estate, according to the court filing, that the production remained faithful to the book.

But after reading another draft in February, Tonja Carter, a lawyer for Lee's estate, said nothing had been done to alleviate their concerns.

After further tense exchanges, a lawyer representing Rudin indicated that his company, Rudinplay, had the final say over the production and that the estate's input was advisory only -- leading to the lawsuit.

The play is due to open on Broadway on December 13 with its first preview on November 1.