The Kite Runner by Khaled Hosseini was near the top of the American Library Association's list of most-challenged books. (Penguin Group USA/Associated Press)

The Kite Runner, Khaled Hosseini's bestseller about a friendship and betrayal between two Afghan boys, is among the most-challenged books of 2008, according to the American Library Association.

The association, which annually issues a list of the most-challenged books, recorded 513 complaints about books in the past year.

But the organization warns that for every formal, written complaint made to a library or school library, there are four or five more informal or unreported complaints.

The Kite Runner drew complaints for its offensive language and sexual content, including the rape of one of the boys.

A parent in Champaign, Ill., and a school board official in Morganton, N.C., were among those who challenged the book.

Successful complaints that resulted in a book being pulled were levied against Sherman Alexie's The Absolutely True Diary of a Part-Time Indian, which refers to masturbation, Jodi Picoult's My Sister's Keeper, deemed too sexually explicit and Mark Bowden's Black Hawk Down, a military tale that contains profanity.

The most-challenged book of the year was And Tango Makes Three, a book about two male penguins who become parents.

Justin Richardson's and Peter Parnell's picture book was criticized for being anti-family, pro-gay and anti-religion.

Similar complaints have been made against other books portraying homosexuality, including classics such as the novel The Color Purple and It's Perfectly Normal, a sex education book that mentions homosexuality.

Other books high on the list are:

• Dark Materials trilogy by Phillip Pullman (violent and anti-religious).
• Gossip Girls series, Cecily von Ziegesar (language, sexually explicit).
• Scary Stories by Alvin Schwartz (violence, occultism).
• The Perks of Being a Wallflower by Stephen Chbosky (drugs, suicide, nudity, language).

The ALA, an organization of American libraries, is an advocate for freer access to reading material.