Facebook is in hot water over its ad targeting technology, with a new report claiming it could until this week be used to easily target anti-Semites.

According to ProPublica, Facebook allowed advertisers to target the news feeds of almost 2,300 people who showed interest in the topics of “Jew hater,” “How to burn jews,” or, “History of ‘why jews ruin the world’”.

To find out if these ad categories were the real deal, ProPublica forked out $30 to target those groups with three “promoted posts” using its articles.

ProPublica claims Facebook signed off on all three ads within 15 minutes, and proceeded to get in touch with the social media giant to issue a ‘please explain’.

“After we 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, such as limiting the number of categories available or scrutinising them before they are displayed to buyers,” the ProPublica article said.