Facebook is updating its self-advertising processes following the discovery by news outlet ProPublica that promoters could target anti-Semitic channels on the site. According to the report, Facebook’s algorithms could be abused to direct pitches to around 2,300 individuals who had expressed interest in topics including ‘Jew hater’, ‘How to burn Jews’, and ‘History of why Jews ruin the world’.

To test if these categories were real, ProPublica – an outlet that specialises in investigative journalism – claims to have paid $30 to target the groups with unrelated adverts. ProPublica asserts that all three ads were approved within 15 minutes, an accusation that was lent credence later that day by a response from Facebook that promised to revise how self-advertising worked on the platform.

Worryingly it appears the site’s algorithm, rather than people, had created the categories – confirming that the self-advertising process can be abused. After they were contacted by ProPublica, Facebook took the self-advertising process offline. In a private response, the site confirmed to ProPublic that it was exploring new methods of delivery, such as limiting the number of categories available or scrutinising them before they were displayed to buyers.

In their public blog post, Facebook said: “Our community standards strictly prohibit attacking people based on their protected characteristics, including religion, and we prohibit advertisers from discriminating against people based on religion and other attributes.”

The site explained that the algorithms had been abused by individuals entering ‘offensive responses’ in their education and employer sections on their profiles. The algorithms then connected these responses to adverts that they might be interested in. Facebook confirmed that ‘an extremely small number’ of individuals had been targeted in these campaigns. According to ProPublica, 5,897 people had been reached by their ads, generating 101 clicks in total.

Facebook’s blog post continued: “To help ensure that targeting is not used for discriminatory purposes, we are removing these self-reported targeting fields until we have the right processes in place to help prevent this issue. We want Facebook to be a safe place for people and businesses, and we’ll continue to do everything we can to keep hate off Facebook.

“Advertisers can report any inappropriate targeting fields directly in the ads interface or via our Help Centre.”