KANSAS CITY, Missouri (Reuters) - A coalition concerned about the cultivation of genetically modified crops in wildlife refuge areas filed suit against the U.S. Interior Department on Wednesday, saying government workers illegally approved the planting.

The lawsuit, filed in U.S. District Court in Wilmington, Delaware, seeks to block further cultivation of the crops at the Prime Hook refuge outside Dover, Delaware. Prime Hook is one of more than 500 federal wildlife refuges.

It named as defendants the U.S. Fish & Wildlife Service and its parent agency, the Interior Department. The plaintiffs are the Delaware Audubon Society, Public Employees for Environmental Responsibility and the Center for Food Safety.

The plaintiffs said they discovered "a top Bush administration political appointee" overruled the wildlife refuge manager in allowing the genetically altered crops to be planted on land designated as a national wildlife refuge in violation of department policy.

Officials with Fish and Wildlife and the Interior Department declined to comment immediately.

The plaintiffs say the genetically modified crops and the pesticides associated with growing them can have negative effects on birds, aquatic animals, other wildlife and plant species.

"These refuges are supposed to be for wildlife, not chemical companies or agribusiness," Gene Hocutt, a spokesman for Public Employees for Environmental Responsibility, or PEER, said in a statement announcing the lawsuit. "Plowing up native grasses for mutated row crops constitutes biological malpractice of the highest order and a betrayal of the purposes of the National Wildlife Refuge System."

As many as 100,000 acres of refuge lands are under cultivation to genetically modified crops, according to agency documents obtained by PEER under the Freedom of Information Act.