Facebook Inc. said it’s disabling an option that let advertisers exclude certain races from their targeting, taking a further step to address concerns about potentially racist ads.

Chief Operating Officer Sheryl Sandberg touted the move in a letter to the Congressional Black Caucus, which she met with earlier this year. The option will be disabled “until we can better ensure that our tools will not be used inappropriately,” she said. The group of black U.S. lawmakers was concerned about a range of issues, from the ad targeting, first exposed by ProPublica, to Facebook’s efforts on workplace diversity.

Sandberg said the company has tightened rules for advertisers in general, especially around divisive and discriminatory content, such as ads that depict violence, sell weapons or attack people based on their race or religion. Facebook said it’s hiring more black and Hispanic people for its global ads review team, which will increase by 1,000 people over the next year.

“This will help increase the diversity of our workforce and improve our understanding and awareness of ads that are meant to exploit culturally sensitive issues,” she said.

The company now has 7,500 people globally removing content that is against its community standards, which are being enforced more strictly. For example, any violent speech directed against people with “protected characteristics” can be taken down. Sandberg didn’t define the protected characteristics, but gave an example of an attack on a woman on the basis of her gender.