A lawsuit filed on Thursday accuses Facebook of letting ad targeting tools be used to exclude women and older people from offers regarding loans, investments and other financial services.
Two law firms have filed a discrimination suit in San Francisco federal court on behalf of a 54-year-old woman living in Washington and will ask a judge to grant the case class-action status.
"Women and older persons are entitled to full and equal services of businesses such as Facebook, and the financial services companies that advertise on Facebook's platform," attorney Matthew Handley said in a statement.
"Purposeful targeting of advertisements away from these members of our community unlawfully denies them these guarantees."
The suit contends that women and older people were denied the benefits of ads for financial services because Facebook tools allow messages to be targeted at specific age ranges or genders.
Facebook said it is reviewing the complaint.
"We've made significant changes to how housing, employment and credit opportunities are run on Facebook and continue to work on ways to prevent potential misuse," a spokeswoman for the leading social network told AFP.
"Our policies have long prohibited discrimination and we're proud of the strides we're making in this area."
Facebook announced earlier this year that it was revamping how it uses targeted advertising in a settlement with activist groups alleging it discriminated in messages on jobs, housing, credit and other services.
Under those changes, housing, employment or credit ads would no longer be allowed to target by age, gender or zip code -- a practice critics argued had led to discrimination.
In the settlement, Facebook agreed to take "far-reaching measures to stop advertisers from using age, gender, and other protected traits to target job, housing, and credit ads," according to the law firms involved in the new suit.
"Today's lawsuit alleges that Facebook has not taken any action to stop advertisers from excluding older persons and women from getting financial services ads on Facebook, other than in the limited area of credit ads," the law firms said.