Facebook has been under fire for its practices and policies that enable advertisers to exclude “multicultural affinity” groups from the audiences they reach via the social network. Now, in light of a ProPublica investigation and pressure from the Congressional Black Caucus, Facebook says it’s committed to taking a closer look at its advertising policies, its COO Sheryl Sandberg wrote in a letter to CBC Chairperson Cedric Richmond.

Until Facebook figures out how to ensure advertisers don’t use its tools in a discriminatory way, Facebook will temporarily disable the option that lets advertisers exclude multicultural affinity groups from their audience. As Sandberg wrote in her letter to the CBC, multicultural affinity groups “are made up of people whose activities on Facebook suggest they may be interested in ads related to the African American, Hispanic American, or Asian American communities.”

Multicultural marketing, Sandberg said in her letter, is common in the ad industry. There are “many legitimate uses for this kind of marketing,” she said, but there are also concerns that advertisers use Facebook to discriminate against people in the areas of housing, employment and credit loans.

“By allowing online advertisers to promote or market a community or home for the purpose of sale to select an ‘ethnic affinity’ as part of their advertising campaign, Facebook is complicit in promoting restrictive housing practices,” members of the CBC said last year.

Facebook said it also will take a look at how advertisers are using exclusion targeting across other “sensitive segments,” like ones that relate to members of the LGBTQ community and people with disabilities.