Having launched an education campaign, an improved reporting procedure and a 24/7 police hotline on Monday, Facebook told the Guardian that it has introduced a number of algorithms that track the behaviour of its users and flag up suspicious activity, including members with a significant number of declined friend requests and those with a high proportion of contacts of one gender.

Another filter, common on web publishing sites, scans photo uploads for skin tones and blocks problem images the "no nipples" filter that caused pictures of breastfeeding mothers to be inadvertently flagged and removed by the site last year.