Up until a few days ago, if you wanted to target an ad to people who considered themselves “Jew haters,” Facebook would let that happen. According to a chilling ProPublica report , Facebook’s self-service ad buying platform included a number of antisemitic categories .

Using what are called “ad categories,” which are automated labels for people on Facebook who share a common trait that advertisers can target, ProPublica was able to find people with specifically antisemitic interests, which included “Jew hater,” “How to burn Jews,” “Nazi Party,” and others. These were all likely automatically created by Facebook users whose interests listed these. Once ProPublica informed Facebook of these categories, it took them down and say it is looking into new measures to keep keep these categories from being used on its ad platform.

Facebook told ProPublica that it looked into the problem and “it’s not common or widespread.” You can read the full report here.

Update: Facebook has provided us with this statement from Rob Leathern, its product management director:

“We don’t allow hate speech on Facebook. 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. However, there are times where content is surfaced on our platform that violates our standards. In this case, we’ve removed the associated targeting fields in question. We know we have more work to do, so we’re also building new guardrails in our product and review processes to prevent other issues like this from happening in the future.”

Update #2: Facebook had announced changes to its ad targeting program. You can read about it here.