NEW YORK (AP) — Facebook may have considered the matter settled, but a group of consumer and children's advocates are renewing their legal battle over teenagers' privacy on the world's largest online social network.

At issue is a 2011 class action lawsuit over Facebook's use of people's images in advertisements known as "sponsored stories." This allowed companies to pay to retransmit users' activities to their friends' pages. If someone clicked the "like" button for a brand, the click could show up as a "sponsored story" on friends' pages.

A federal court approved a settlement last August.

But the nonprofit Public Citizen and six parents of teenagers on Thursday filed a legal brief in a federal appeals court in California saying the proposed settlement should be rejected.