Harper Lee: Tributes pour in for To Kill a Mockingbird author who has died aged 89

Ava DuVernay, Tim Cook and John Green paid tribute on social media

Lee receiving a Presidential Medal of Freedom in 2007 (Chip Somodevilla/Getty Images)

Harper Lee, the author of To Kill a Mockingbird and Go Set a Watchman, has died aged 89.

The Mayor's office of her hometown in Monroeville, Alabama, confirmed her passing to the Press Association news agency.

Many tributes have since been paid to the Pulitzer prize-winning author whose powerful 1961 novel dealt with race relations in the America's Deep South.

Among those who led tributes were Selma director Ava DuVernay and author of The Fault In Our Stars, John Green.

The CEO of Apple, Tim Cook, also paid tribute, as did Erin Brockovich who said it is important to remember to "stand up for what's right".

Actresses Ariel Winter and Debra Messing also paid tribute with Messing, best known for her lead role in Will and Grace, saying Lee "changed the world" with To Kill a Mockingbird.

The publishers of Go Set a Watchman, Harper Collins, said they will "forever be thankful" for her writing and Penguin Random House publishing group also expressed sentiments on Twitter.