LOS ANGELES (Reuters) - The best-selling vampire themed “Twilight” book series has entered the top 10 list of books that U.S. schools and public libraries were asked to remove from their shelves in 2009.

Author Stephenie Meyer poses at the premiere of the movie "Twilight" at the Mann Village and Bruin theatres in Westwood, California November 17, 2008. REUTERS/Mario Anzuoni

But the worst offenders were the popular young adult novel series “ttyl” by Lauren Myracle, which are written entirely in the style of instant messages, the American Library Association (ALA) said in a report on Wednesday.

And although they are no longer in the Top 10, J.K. Rowling’s “Harry Potter” series landed atop the 100 most frequently challenged books of the 2000-2009 decade. Objections to the best-selling tales of the boy wizard have been raised over perceived anti-family and occult themes.

The ALA said Stephenie Meyer’s “Twilight” series, which have been turned into a blockbuster film franchise, were fifth on the 2009 list -- their first year in the annual compilation. The books were challenged for being sexually explicit, religious views and being unsuitable for their age group.

The “ttyl” series, which came top of the 2009 list, was challenged for nudity, offensive language and drugs.

The ALA’s Office for Intellectual Freedom defines a challenge as a formal written complaint filed with a library or a school requesting that material be removed from bookshelves or a school curriculum. It received 460 such reports in 2009 and they come from a variety of sources. Few are successful.

“Even though not every book will be right for every reader, the ability to read, speak, think and express ourselves freely are core American values,” said Barbara Jones, director of the ALA’s Office for Intellectual Freedom.

The children’s picture book “And Tango Makes Three” about two male penguins raising an egg, and teen novel “The Perks of Being a Wallflower” took the No. 2 and No. 3 spots in 2009.

Harper Lee’s 1960 Pulitzer Prize winning classic “To Kill a Mockingbird” came fourth because of challenges on the grounds of racism and language.

The top 5 most frequently challenged books of 2009 were:

1: “ttyl”, “ttfn”, “l8r”, “g8r” (series) by Lauren Myracle

2: “And Tango Makes Three,” by Pater Parnell and Justin Richardson

3: “The Perks of Being a Wallflower,” by Stephen Chbosky

4: “To Kill A Mockingbird”, by Harper Lee

5: “Twilight” (series), by Stephenie Meyer