SIOUX FALLS - Two Native American tribes in South Dakota are expected to file a class action lawsuit Thursday alleging that the state's Department of Social Services has violated the Indian Child Welfare Act.

The federal law requires that Native American children removed from homes be placed with relatives or put in foster care with other Native American families except in unusual circumstances.

The Oglala Sioux Tribe and the Rosebud Sioux Tribe are set to file the lawsuit in federal court in Rapid City.

The Department of Social Services has acknowledged a disproportionate number of Native American children are involved in the child welfare system. Officials say this is because the state receives more referrals for alleged abuse and neglect involving Native American children.

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