The global illegal trade in wildlife is worth $19 billion a year and some of that money from trafficking is being used to finance civil conflicts, the WWF said.
The risk is being made worse by a "new wave" of organized wildlife crime carried out by well-funded and well-armed groups operating across national borders, the group said.
"This is about much more than wildlife," said Jim Leape, WWF International director general. "This crisis is threatening the very stability of governments. It has become a profound threat to national security."
Rebel militia groups in Africa are taking advantage of the global demand for elephants, tigers and rhinos to fund civil conflicts, the BBC quoted John Scanlon of Cites, the organization that governs the trade in endangered species, as saying.
"We saw earlier this year with rebel groups coming from Chad and Sudan going into northern Cameroon slaughtering 450 elephants, taking the ivory for the purpose of selling it in order to buy arms for local conflicts" Scanlon said, also citing similar reports from the Democratic Republic of Congo.
The illicit sale of animals and plants is the fourth largest illegal trade globally after narcotics, counterfeiting and human trafficking, the WWF said.