A spokeswoman for online retail giant Amazon is blaming a computer glitch for the "sales rank" removal of gay and lesbian themed books, news of which spread rapidly across social networks like Twitter and Facebook this weekend.

"There was a glitch in our systems and it's being fixed," Amazon's director of corporate communications, Patty Smith, said in an email on Sunday.

"We're working to correct the problem as quickly as possible," she said, but refused to share further details about the nature of the glitch.

News that Amazon.com had de-listed gay and lesbian book titles from its sales ranking system — apparently because they had been deemed adult content — raced across the blogosphere and through online communities on Sunday, with furious internet users accusing the company of censorship.

Amazon's sales ranking system denotes how well a book sells in comparison to others. Though a title could still available for purchase, if the sales rank is removed, it would not show up in Amazon's tallies — even if it were the site's top-selling item. De-listing also removes the affected title from some searches.

Books that were de-listed included James Baldwin's Giovanni's Room, Gore Vidal's The City and the Pillar, Virginia Woolf's Orlando, Little Birds by Anais Nin, Paul Monette's Becoming A Man, Jeanette Winterson's Oranges Are Not the Only Fruit and the biography of talk show host and comedian Ellen DeGeneres.

However, infuriated online posters and bloggers noticed that numerous books with heterosexual adult content did not lose their sales ranking.

Others discovered that the de-listing was inconsistent. For instance one publisher's edition of a book was removed but another's wasn't, as bloggers discovered with different editions of The Diving Bell and the Butterfly by Jean-Dominque Bauby and with different editions of E.M. Forster's Maurice.

Craig Seymour, who wrote a memoir entitled All I Could Bare about his past as a gay stripper, noted on his blog that when his book's sales rank was dropped in February, he questioned the decision and was informed that his book had been classified as an adult product.

Incidentally, Juno screenwriter Diablo Cody's memoir Candy Girl, about her experiences as a stripper, was not de-listed.

After Seymour protested, his sales ranking was eventually restored.

With files from the Associated Press