A group of hunting advocacy groups is suing Delta Airlines over its recent ban on transporting big game trophies from Africa.

Dallas Safari Club and three fellow conservation organizations, including the Tanzania Hunting Operators Association and the Houston Safari Club, along with big game hunter Corey Knowlton argue in their lawsuit filed October 20 that as a so-called "common carrier" Delta Airlines is obligated to not discriminate against passengers or cargo, including legally obtained big game trophies. The plaintiffs are asking for a judge to lift the embargo and have asked for Delta to compensate outfitters who've lost business because of the ban.

"Delta is a common carrier. It cannot discriminate against cargo, the African people, or game – much less to further the agenda of extremist animal rights organizations," said John Jackson, president of Conservation Force, which is a party to the complaint. "Its embargo threatens the programs responsible for most of the habitat and anti-poaching in Africa."

Delta has previously declined comment on the lawsuit.

Delta's restriction on flying the so-called "Big Five" wild game trophies from Africa — including lion, leopard, rhino, elephant and buffalo — came after anti-hunting groups put pressure on airlines in the wake of the "Cecil the Lion" scandal. The killing of the Zimbabwean lion by Minnesota dentist Walter Palmer this summer prompted outrage from animal rights groups who used the high-profile killing to lobby businesses and governments to ban big game hunting.

Palmer has since been cleared by Zimbabwean game officials of any wrongdoing.

The lawsuit against Delta also stems from difficulties encountered by Corey Knowlton, a big game hunter who paid $350,000 in a charity raffle to hunt a Black Rhino in Namibia a year ago and has been unable to ship his trophy home.

" 'Big Five' hunting in Southern and Eastern African is responsible for protecting the most wildlife habitat, providing the largest share of operating revenue for state wildlife departments, underwriting the three levels of anti-poaching efforts, and contributing critical benefits and incentives to local people," the pro-hunting groups say. "Delta’s embargo threatens the African hunting industry by making it more difficult for hunters to bring home the fruit of the hunt, and stigmatizes America’s business and civic leaders as traffickers of illicit cargo."