Facebook is under scrutiny from US Reps. Keith Ellison and John Conyers.
The two Democrats wrote a letter to the social media company on Wednesday asking that it update its policies regarding hate speech. They also asked Facebook to clarify who buys ads on its site and to make all Facebook ads publicly available.
Ellison of Minnesota and Conyers of Michigan wrote that they are "concerned that Facebook allowed advertisers to target people who expressed interest in the topics of 'Jew-hater' and 'How to burn jews.'"
"Allowing for the spread of violent and hateful ideologies on Facebook, a network with nearly 2 billion unique users, poses a grave threat to not only our most marginalized and threatened communities, but to our entire civil society," they wrote.
Facebook defines hate speech as attacks on people based on their race, sexual orientation and/or other "protected characteristics." The company has said it grapples with tens of thousands of hateful posts per week and depends on its billions of users to report any posts that may violate its rules.
Ellison and Conyers said Facebook's current policies regarding hate speech are "troubling."
"While it earned revenue by letting advertisers target individuals who shared vile anti-Semitic statements, it was also banning Black women who spoke out against racism," they wrote.
The congressmen were referring to an incident when activist and writer Ijeoma Oluo's Facebook account was suspended after she posted a series of screenshots of threatening and racist messages she'd received. Facebook later reinstated her account. It appears that wasn't an isolated incident, according to TechCrunch. Several other black activists have reported similar occurrences.
In their letter, Ellison and Conyers sent Facebook a number of questions involving how it identifies hate speech and what it does to prevent its spread on its advertising platform. They also asked that Facebook detail any changes it recently made to its policies.
Facebook didn't immediately respond to a request for comment.
iHate: CNET looks at how intolerance is taking over the internet.
Special Reports: CNET's in-depth features in one place.