Facebook has said it will review how it deals with "controversial, harmful and hateful" content after admitting current measures are not effective.

The admission follows sustained pressure from campaign groups, advertisers and the media.

An open letter from several feminist groups urged Facebook to ban pages that they said promoted violence.

In a blog post, the social network said: "We need to do better - and we will."

The company said it would begin rolling out changes immediately after it became "clear that our systems to identify and remove hate speech have failed to work as effectively as we would like".

Marne Levine, Facebook's vice president of Global Public Policy, added: "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"In other cases, content that should be removed has not been or has been evaluated using outdated criteria.

"We have been working over the past several months to improve our systems to respond to reports of violations, but the guidelines used by these systems have failed to capture all the content that violates our standards."

BBC News