The campaign gathered momentum, however, when tens of thousands of tweets and emails using the hashtag #Fbrape were sent to the social network's advertisers.
At least 15 pulled their ads, Women, Action and the Media said, including Nissan UK, Nationwide UK, J Street and WestHost.
It said it had miscalculated the balance. "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 In other cases, content that should be removed has not been or has been evaluated using outdated criteria. 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."
