Free speech organisations step in after The Absolutely True Diary of a Part-Time Indian is pulled from high-school reading lists for 'filthy words' and anti-Christian content

The award-winning author Sherman Alexie has slammed education authorities for wanting to "control debate and limit the imagination" after his acclaimed novel The Absolutely True Diary of a Part-Time Indian was pulled from the curriculum in Idaho schools.

The multiple award-winning young-adult novel, which tells of how Junior leaves his school on the Spokane Indian Reservation to attend an all-white high school, has come under fire in the past for reasons ranging from offensive language to sexually explicit scenes. Now, following parental objections, the school board in the Meridian district in Idaho has voted to remove it from the high-school supplemental reading list, where it has been used since 2010, reported local paper the Idaho Statesman.

One local said it subjects children to filthy words "we do not speak in our home", reported the paper, which said the book features "reference to masturbation, contains profanity and has been viewed by many as anti-Christian".

The move was protested by students – one brought a petition with 350 signatures asking the board to keep the book, said the Idaho Statesman, saying that "our education is being censored" – but the majority of locals at the board meeting to discuss the title were against keeping it on the curriculum.

The decision to ban The Absolutely True Diary of a Part-Time Indian has been condemned by free speech organisations in the US, with a letter from the National Coalition Against Censorship yesterday calling on the board to reverse its decision.

"The book is widely taught in high schools across the country because of its appeal to reluctant readers. The novel addresses vital issues such as the struggles of young adulthood, the search for personal identity, bullying and poverty. It is ultimately an uplifting story of triumph by a boy with few advantages," runs the letter, also signed by Alexie's publisher, Little, Brown Books for Young Readers.

Removing the novel "because some object to, or disapprove of, its content violates basic constitutional principles", they say, and under the First Amendment, "school officials have much wider discretion to include material that has pedagogical value than to exclude it".

"Students have the right to read affecting, engaging and valuable works and teachers have the right include them in their curriculum," said NCAC executive director Joan Bertin. "Public education should not be subject to the personal views and preferences of individuals, nor should access to a high-quality education be obstructed by government officials."

Alexie said that "book banners want to control debate and limit the imagination. I encourage debate and celebrate imagination".

The Idaho ban is the latest in a series of attacks on the novel: the National Coalition Against Censorship said that The Absolutely True Diary of a Part-Time Indian is its most frequently defended title, with six challenges or bans to the book in the last six months alone.

"It's hard to imagine that anyone who has read Alexie's book in its entirety would try to have it banned. Some of the main character's frank comments – about masturbation, questioning God – make adults uncomfortable. But we can't hide things from young people, 16-year-olds in this case, because they might be uncomfortable to think or talk about," said the organisation's spokesperson Acacia O'Connor.

"Lately there's been a lot of talk in American school districts about choice and it centers almost exclusively on parents, without taking into account that young people themselves are individuals with rights to a quality education and to access to information."