Consumer advocates accused companies including McDonald's Corp and Viacom Inc's Nickelodeon of unlawfully using children to market their websites through campaigns that encourage sharing video, games and other content.

The Center for Digital Democracy and 16 other groups asked the U.S. Federal Trade Commission to investigate, accusing the companies of violating the Children's Online Privacy Protection Act (COPPA) by asking children to divulge personal information and the information of friends without parental consent.