(Reuters) – Three female former employees of Alphabet Inc’s (GOOGL.O) Google filed a lawsuit on Thursday accusing the tech company of discriminating against women in pay and promotions.

The proposed class action lawsuit filed in California state court in San Francisco comes as Google is facing a sex bias investigation by the U.S. Department of Labor.

The plaintiffs are a former Google software engineer, a former communications specialist and a former manager who worked in various roles at the Mountain View, California-based company. They claim Google pays women in California less than men who perform similar work, and assigns female workers jobs that are less likely to lead to promotions.

Google did not immediately respond to a request for comment.