A row over sexually explicit content on the web encyclopaedia Wikipedia and related sites has escalated.
Co-founder Jimmy Wales has given up some of his site privileges following protests by contributors angered that he deleted images without consultation.
Mr Wales had previously urged the removal of "pornographic" content from the user-generated site.
This followed a complaint about "child pornography" to the FBI from another Wikipedia co-founder.
In early April, the estranged co-founder, Larry Sanger, reported Wikimedia Commons to the FBI, alleging that the organisation was "knowingly distributing child pornography".
He later clarified that his concern was not about photographs of children, but "obscene visual representations of the abuse of children", which can include drawings and sculpture.
Sexually explicit content
Last week, administrators of Wikimedia Commons, a media file store widely used for Wikipedia articles, deleted hundreds of images.
Some images deemed by the Wikipedia community to have educational merit have since been reinstated.
Mr Wales had earlier posted his support for the removal of "images that are of little or no educational value but which appeal solely to prurient interests", deleting many pictures himself.
Pressure on the organisation had increased after Fox News reported the story, contacting a number of high-profile corporate donors to the Wikimedia Foundation, which owns Wikipedia, Wikimedia Commons and related sites.
It asked whether the donors were aware of "the extent of sexually explicit content" on Wikimedia Commons.
It is not clear whether Mr Wales's support for the removal of explicit content was in response to Mr Sanger's concerns, pressure from Fox News, or something else.
But Michael Peel, Chair of Wikimedia UK, told BBC News that a continuous debate over explicit content has recently "come to a head". The central issue at the moment, he says, is "whether the content is educational".
"Anyone can come to Wikimedia Commons and upload media. Illegal stuff is deleted, and copyright stuff is deleted."
Mr Wales has faced criticism from the band of volunteers who help to maintain the site, some of whom argued that the decision to delete was undemocratic and taken too quickly. They also expressed concerns that valid material might be deleted accidentally.
On Sunday, in response, Jimmy Wales voluntarily revoked many of the "permissions" given to him as Wikipedia's founder, to delete and edit "protected" content on Wikimedia Commons.
In a message to the Wikimedia Foundation mailing list he said this was "in the interest of encouraging this discussion to be about real philosophical/content issues, rather than be about me and how quickly I acted".
A more detailed policy statement from the Wikimedia Foundation is expected in the coming days.