NEW YORK — A coalition of more than 20 consumer advocacy groups is expected to file a complaint with federal officials Monday claiming that YouTube has been violating a children’s privacy law.

The complaint contends YouTube, a Google subsidiary, has been collecting and profiting from the personal information of young children on its main site, although the company says the platform is meant only for users 13 and older.

The coalition said YouTube has failed to comply with the Children’s Online Privacy Protection Act, which requires companies to get consent from parents before collecting data on children younger than 13.

The groups are asking for a Federal Trade Commission investgation and penalties.

“Google has been continually growing its child-directed service in the United States and all over the world without any kind of acknowledgment of this law and its responsibilities,’’ said Jeffrey Chester, executive director of the Center for Digital Democracy, one of the groups leading the coalition. “It’s living in a world of online fiction and denied that it’s serving children.’’

YouTube defines its main site and app as destinations for viewers 13 and older. It directs younger children to the stand-alone YouTube Kids app, which contains a filtered set of videos from the main site. YouTube’s distinction between its main product and YouTube Kids is significant because of the rules on disclosure and parental consent that kick in for sites with “actual knowledge’’ they are trafficking in the personal information of children under 13.

Those rules were first detailed in the Children’s Online Privacy Protection Act of 1998, known as COPPA. The FTC expanded the act in 2012, noting that it needed to be updated for the age of mobile devices. The revised rules made clear that companies must obtain parental consent before collecting details that could be used to identify, contact, or locate a child. These included photos, video, audio, and the location of a child’s mobile device.

In the complaint that will be filed Monday, the advocacy groups say YouTube is able to collect data on children under 13 through its main site, where cartoons, nursery-rhyme videos, and those ever-popular toy-unboxing clips garner millions of views. YouTube’s terms of service hold that visitors to its main site are affirming that they are at least 13 and agree to Google’s privacy policy.