Six Black farmworkers in Mississippi say in a new lawsuit that their former employer brought white laborers from South Africa to do the same jobs they were doing and that the farm has been violating federal law by paying the white immigrants more for the same type of work.

Mississippi Center for Justice and Southern Migrant Legal Services filed the federal lawsuit Wednesday on behalf of the six workers against Pitts Farm Partnership, which grows cotton, soybeans, and corn in the Mississippi Delta’s Sunflower County.

The lawsuit said the farm violated regulations of a foreign worker visa program, which requires equal treatment of U.S. workers and their immigrant counterparts. It seeks an unspecified amount in damages, including money the U.S. workers say they were shorted because of the uneven pay scale.

The Associated Press left messages by phone and email with Pitts Farms seeking comment about the lawsuit. There was no immediate response by Thursday afternoon.