Doctors Without Borders (MSF) delivered a petition with 547,000 signatures to the White House on December 9 demanding an independent investigation into U.S. air strikes at its hospital in Kunduz, Afghanistan.
The October 3 bombing killed at least 30 people, including 14 staff members, and destroyed the hospital, which was the only trauma center in northern Afghanistan.
The United States and NATO are investigating the incident, which U.S. military commanders have said appeared to be primarily the result of human error.
But the military investigations have not satisfied MSF. It wants a probe by the International Humanitarian Fact-Finding Commission.
"It is not sufficient for the perpetrators of attacks on medical facilities to be the only investigators," said Jason Cone, executive director of MSF-USA. "Only a full accounting by an independent, international body can restore our confidence" that the laws of war will be upheld.
MSF has accused the U.S. military of "gross negligence."
Human Rights Watch and the European Parliament have also called for an independent investigation.
With reporting by AFP