First published in July 1960, Mockingbird has sold more than 30m copies worldwide, and that total is climbing by more than 1m copies a year, according to HarperCollins.

Harper Lee agrees to ebook version of To Kill a Mockingbird

Author announces on her 88th birthday that novel will be released as ebook and downloadable audiobook on 8 July

The Guardian (UK) | 28 April 2014 

Harper Lee in 2007. Photograph: Rob Carr/AP

Harper Lee has agreed for To Kill a Mockingbird to be made available as an ebook and digital audiobook, filling one of the biggest gaps in the digital library.

To Kill A Mockingbird: 50th Anniversary edition
by Harper Lee

In a rare public statement released through her publisher, HarperCollins, Lee said: "I'm still old-fashioned. I love dusty old books and libraries. I am amazed and humbled that Mockingbird has survived this long. This is Mockingbird for a new generation."

The announcement came almost a year after she sued her former literary agent Samuel Pinkus to regain rights to her novel. Lee claimed she had been duped into signing over the copyright.

The lawsuit was settled in September. Lee's attorney, Gloria Phares, said at the time that the case had been resolved to the author's satisfaction, with "her copyright secured to her".

The Pulitzer prize-winning novel will be released digitally on 8 July.

With digital holdouts from JK Rowling to Ray Bradbury changing their minds over the past few years, Lee's novel had ranked with JD Salinger's Catcher in the Rye as a missing prize for ebook readers.

First published in July 1960, Mockingbird has sold more than 30m copies worldwide, and that total is climbing by more than 1m copies a year, according to HarperCollins.

It was adapted into a 1962 movie of the same name that featured an Oscar-winning performance by Gregory Peck as Atticus Finch, the courageous Alabama attorney who defends a black man against charges that he raped a white woman.

Lee never published another book, which only seemed to add to the novel's appeal, and for decades she has resisted interviews and public appearances. She turned 88 on Monday and lives in her native Alabama.

Michael Morrison, of HarperCollins, said: "Every home has a dog-eared copy of To Kill a Mockingbird, and now readers will be able to add this favourite book to their digital libraries. Although today is Nelle Harper Lee's birthday, she is giving readers around the world the gift of being able to read or listen to this extraordinary story in all formats."

The ebook will be published by Cornerstone in the UK. Susan Sandon, Cornerstone managing director, said: "To Kill a Mockingbird regularly tops polls as the nation's most-loved book and we are delighted that readers all over the world will now have the opportunity to read or listen to this very special book in all formats."

The audiobook will be a downloadable edition of the existing CD narrated by Sissy Spacek. HarperCollins is also releasing an "enhanced" ebook that will feature additional material. Spokeswoman Tina Andreadis said the extra features had not yet been determined.

Other works still unavailable as ebooks include The Autobiography of Malcolm X and Gabriel García Márquez's One Hundred Years of Solitude.