A U.S. consumer group is suing McDonald's Corp. in an effort to stop the world's largest hamburger chain from using Happy Meal toys to lure children into its restaurants.

The move makes good on a threat made in June by the Center for Science in the Public Interest.

The class-action suit will to be filed Wednesday in state court in San Francisco on behalf of Monet Parham, a mother of two who claims that her young children ask to go to McDonald's to get toys based on characters like Barbie, i-Carly, Shrek and Strawberry Shortcake, CSPI said.

Representatives from McDonald's were not immediately available for comment.

Parham is being represented by CSPI's litigation unit and by private attorney Richard Baker of Baker Law P.C. in Birmingham, Alabama.

The suit will allege violation of California's consumer protection laws and will be filed in California Superior Court for the district of San Francisco, CSPI said.