The UN Office of the High Commissioner for Human Rights has launched an investigation into drone strikes and will review resultant civilian casualties to determine whether the attacks constitute a war crime.

Ben Emmerson, a UN special rapporteur on human rights and counter-terrorism, formally launched the inquiry on Thursday, in response to requests from Russia, China and Pakistan.

"This is not an investigation into the conduct of any particular state. It's an investigation into the consequence into this form of technology," Emmerson told Al Jazeera.