Gay and lesbian groups are demanding explanations from Amazon after the online bookstore delisted hundreds of books this month because they contained 'homosexual themes'.

Over 57,000 titles have been involved in the delisting - with books losing their Amazon sales rank.

Books affected by Amazon's seemingly heavy-handed censoring included modern American classics such as James Baldwin's Giovanni's Room and Brokeback Mountain by Annie Proulx, as well as books by Jeannette Winterson, Alan Hollinghurst and Gore Vidal.

Conspiracy or glitch?

Denying the existence of a right-wing conspiracy within the organisation to purge its offering of gay and lesbian literature, Amazon is claiming that the delisting was due to an admit error.

"This is an embarrassing and ham-fisted cataloging error for a company that prides itself on offering complete selection," noted Amazon spokeswoman Patty Smith.

"This problem impacted books not just in the United States but globally.It affected not just sales rank but also had the effect of removing the books from Amazon's main product search."

Rankings are vital to sales of an author's book, as they affect the ways the title appears (or doesn't) in searches. A higher-ranked title is likely to sell a lot more copies.

Glitch or not, an online petition of consumers unhappy with Amazon's new policy on adult literature is already up and running.