Facebook will review the way it moderates posts after a spate of incidents involving hate speech towards women caused a major advertiser to withdraw from the social network.
Facebook is under pressure to prove its effectiveness as an advertising platform to justify its over $100bn flotation value.
An outcry over Facebook groups apparently endorsing the rape and murder of women, and a separate spate of "Rate Your Shag" pages popularised by university students, have left the Californian social network scrambling to respond in recent days.
Facebook finally acted last night after a week in which British building society Nationwide, Japanese car manufacturer Nissan and Unilever's Dove brand all suspended advertising on the site.
Adverts for their products appeared next to a group captioned "I like her for her brains" below a woman lying with a pool of blood around her head, and another titled "Violently Raping Your Friend Just for Laughs".
Activists from groups such as the UK's Everyday Sexism Project and the US-based Women, Action and the Media (WAM!) led a campaign that saw 5,000 emails and 60,000 tweets directed at the companies, urging them to withdraw advertising until Facebook changed its policy on images and sentiments of gender-based violence appearing on the site.
A statement from Facebook admitted it had failed to prevent hate speech appearing on the network, and promised to update user guidelines, improve moderator training and increase accountability by forcing those posting "cruel or insensitive" content to attach their real identity to their posts.
More formal links with women's groups and US Jewish rights group the Anti-Defamation League would also be initiated, Facebook added.
A spokesman said: "Facebook’s mission has always been to make the world more open and connected. We seek to provide a platform where people can share and surface content, messages and ideas freely, while still respecting the rights of others.
"In recent days, it has become clear that our systems to identify and remove hate speech have failed to work as effectively as we would like, particularly around issues of gender-based hate.
"In some cases, content is not being removed as quickly as we want. In other cases, content that should be removed has not been or has been evaluated using outdated criteria."
Jaclyn Friedman, executive director of WAM!, said: “We are reaching an international tipping point in attitudes towards rape and violence against women. We hope that this effort stands as a testament to the power of collaborative action.”
Separately, a spate of "Rate Your Shag" pages, where users were encouraged to give their sexual partners a mark out of ten for performance, were removed yesterday after appearing on Facebook.
The pages sparked a privacy row after the anonymous postings were said to reveal the real identities of users' sexual partners. Universities including Warwick, Loughborough and Bournemouth all had "Rate Your Shag" pages created by students removed.