Harper Lee, who wrote one of America's most enduring literary classics, To Kill a Mockingbird, about a child's view of right and wrong and waited 55 years to publish a second book with the same characters from a very different point of view, has died at the age of 89.

Mary Jackson, the city clerk in Lee's hometown of Monroeville, Alabama, confirmed to Reuters by phone that Lee had died.

For decades it was thought Lee would never follow up To Kill a Mockingbird and the July 2015 publication of Go Set a Watchman was a surprising literary event - as well as a shock for devotees of Mockingbird.

In the first book, Atticus Finch was the adored father of the young narrator Scout and a lawyer who nobly but unsuccessfully defended a black man unjustly accused of raping a white woman. But in Watchman, an older Atticus had racial a views that left the grown-up Scout greatly disillusioned.

Lee reportedly had written Go Set a Watchman first but, at the suggestion of a wise editor, set it aside to tell a tale of race in the South from the child's point of view in the 1930s.

For many years, Lee, a shy woman with an engaging Southern drawl, lived quietly and privately, always turning down interview requests. She alternated between living in a New York apartment and Monroeville, where she shared a home with her older sister, lawyer Alice Lee. After suffering a stroke and enduring failing vision and hearing, she spent her final years in an assisted-living facility in Monroeville.

Lee's state of mind would become an issue when plans were announced in 2015 to publish Go Set a Watchman. Some friends said that after the death of Alice, who handled Harper's affairs, lawyer Tonja Carter, had manipulated Lee to approve publication.

Carter had said she came across the Watchman manuscript while doing legal work for Lee in 2014 and an investigation by Alabama state officials found there was no coercion in getting Lee's permission to publish.

Lee's literary output had been a matter of speculation for decades before Go Set a Watchman. She acknowledged she could not top the Pulitzer Prize-winning Mockingbird but friends said she had worked for years on at least two other books before abandoning them. A family friend, the Reverend Thomas Lane Butts, told an Australian interviewer Lee had said she did not publish again because she did want to endure the pressure and publicity of another book and because she had said all that she wanted to say.