The Apple iPad is examined after its unveiling at the Moscone Center in San Francisco, Wednesday, Jan. 27, 2010. (AP Photo/Marcio Jose Sanchez)

London - Rules that govern what Facebook's 845 million users can post have been leaked, leaving the social networking website red-faced.

The edicts that dictate what content is deleted by staff after being “flagged” by Facebook users had been a strictly guarded secret.

A disgruntled Moroccan employee leaked the Abuse Standards Violations (ASV), revealing a relaxed attitude towards violence.

The US website published the standards on Tuesday night.

“Naked private parts including female nipple bulges and naked butt cracks[,] male nipples are okay,” the document said. “Crushed heads, limbs, etc, are okay as long as no insides are showing.”

But even pixelated nudity is banned such as “mothers breastfeeding without clothes”.

Facebook's zealousness in deleting users' content has previously led to criticism. In April last year the website was accused of homophobia when it deleted a gay kiss. This month, so-called “lactivists” protested outside the company's US and London headquarters at its deletion of breastfeeding photos. Facebook said breastfeeding photos were permitted as long as “no part” of the nipple was showing.

Users are allowed to post images of marijuana unless the poster is selling the drug. “Any depiction of marijuana alone (any amount) or implements used for smoking marijuana are ok,” the leaked ASV said.

A Facebook spokesman would not confirm how many outsourcing companies were employed to monitor content and would not comment on how much these employees were paid. He said: “In an effort to quickly and efficiently process the millions of reports we receive every day, we have found it helpful to contract third parties to provide precursory classification of a small proportion of reported content.” - The Independent