San Francisco, Sep 15 (IANS): After courting controversy for enabling Russia-controlled accounts to buy ads before the 2016 US presidential election, it has now come to light that the social network also enabled advertisers to reach "Jew haters" until this week.

Facebook enabled advertisers to direct their pitches to the news feeds of almost 2,300 people who expressed interest in the topics of "Jew hater," "How to burn jews," or, "History of 'why jews ruin the world", a ProPublica investigation has revealed.

To test if these ad categories were real, the nonprofit newsroom paid $30 to target those groups with three "promoted posts". Facebook approved all three ads within 15 minutes.

After ProPublica, a recipient of the 2017 Pulitzer Prize for public service, contacted Facebook, it removed the anti-Semitic categories -- which were created by an algorithm rather than by people -- and said it would explore ways to fix the problem.

"There are times where content is surfaced on our platform that violates our standards," Rob Leathern, Product Management Director at Facebook was quoted as saying.

"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," Leathern added.

Facebook recently acknowledged that Russian-controlled pages and accounts spent $100,000 on ads meant to "amplify divisive social and political messages" before the US presidential election.

Unlike traditional media companies that select the audiences they offer advertisers, Facebook generates its ad categories automatically based both on what users explicitly share with Facebook and what they implicitly convey through their online activity, ProPublica reported on Thursday.