Christof Heyns, a U.N. Special Rapporteur, said at a recent panel discussion that drones were not technically an illegal weapon, but allowing the United States to use them for whatever reason they wanted to could lead to other countries deploying them as well.
"A world where multiple states use such weapons in secrecy is a less secure world," Heyns said.
The United Nations said in a written statement that Heyns recently compiled a report saying human rights and international law must be respected as drones become a weapon that alters the definition of war zones.
Heyns' report came out about the same time Pakistan's ambassador to the United Nations publicly called on the United States to halt its drone campaign against Taliban and al-Qaida elements in his country.
Notable deaths of 2014 [PHOTOS]