AN American school district has reportedly taken the unusual step of banning the hit book series Outlander.

The best-selling novels are said to be among 58 set to be removed from all libraries in Florida’s Walton County school district.

The novels, written by American Diana Gabaldon, inspired the popular TV programme of the same name.

They follow an English nurse who time travels to 18th-century Scotland and becomes embroiled in the Jacobite uprising. The series has sold more than 25 million copies since its release in 1991.

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While the district hasn’t stated the specific reason for the ban of each book, much of the list explores sexuality and gender.

Among the books listed to be removed are popular teen novels Normal People by Sally Rooney and Thirteen Reasons Why by Jay Asher. 

50 Shades of Gray by E L James also appears on the list.

Other books include Being Jazz, My Life as a Transgender Teen by Jazz Jennings, Two Dads by Carolyn Robertson, Mommy, Mama and Me by Leslie Newman and Celebrate Your Body 2: The Ultimate Puberty Book for Preteen and Teen Girls by Lisa Klein and Carrie Leff.

Defending the ban, one local official said it was “necessary” for the “welfare of all involved”.

Local news outlet WJHG reported Walton County School superintendent A Russell Hughes as saying: “What is necessary varies.

"I don’t know if I define the word ‘necessary’ as necessary to those who are opposing, necessary to those who didn’t want to, it was necessary in this moment for me to make that decision and I did it for just a welfare of all involved, including our constituents, our teachers, and our students. I’ll continue to do those things and perhaps add some.”

A picture of the 58 banned books shared online has prompted fury.

Responding to her book being banned, author Lauren Groff tweeted: "My book Fates and Furies is number 49 on this banned books list, probably because it contains consensual adult sex and an abortion.

"If any public school students in Walton County want to sneak my book onto their school library shelves, I’d be glad to mail you a copy."

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Others pointed out that many of the books on the list feature LGBT characters and narrators.

American TV writer Melissa Jo Peltier said: "So Walton County Fla bans TWO Toni Morrison books, ‘The Kite Runner’ (??), Jodi Picoult’s ‘19 Minutes’ (school shooting), ‘Extremely Loud & Incredibly Close’(about 911 aftermath), & a ton of books [with LGBT] narrators or protagonists. Banning books is a form of authoritarianism."

Another social media user said: "Book banning reveals an ugly, incurious and moralistic streak, but this strategy remains mired in the pre-Internet era.

"All these titles are easily accessible online, so congrats on your non-achievement, Walton County. Unless you count inadvertently creating a great reading list."