GRAND ISLAND, Neb. (AP) — A teachers union has accused the Grand Island Public Schools district of misclassifying several teachers as substitutes, even though they essentially work as full-time teachers.

The Grand Island Education Association said that’s an unfair labor practice that underpays those teachers by up to several thousand dollars.

The association says in a news release that it has filed a complaint over the practice with Nebraska’s Commission of Industrial Relations.

The district defended itself in a statement to the Grand Island Independent, saying it’s “confident that we are operating in good standing with the terms of our existing agreement.”