New York, US (BBN)-Aid agency Medecins Sans Frontieres is seeking to invoke a never-used body to investigate the US bombing of its hospital in the Afghan city of Kunduz.
MSF said it did not trust internal military inquiries into the bombing that killed at least 22 people, reports BBC.
The International Humanitarian Fact-Finding Commission was established in 1991 under the Geneva Conventions.
The US says last Saturday’s bombing was a mistake. It came amid efforts to reverse a Taliban takeover of Kunduz.
On Tuesday, Gen John Campbell, US commander of international forces in Afghanistan, said the attack had been requested by Afghan forces who were in communication with American special operations troops at the scene.
Those US forces in turn were in contact with the AC-130 gunship that fired on the hospital, he said.

“We would never intentionally target a protected medical facility,” Gen Campbell told the Senate Armed Services Committee in Washington.
A number of inquiries have been ordered – by the US Department of Justice, the Pentagon, Nato and an American-Afghan team.
But MSF chief Joanne Liu told reporters in Geneva: “We cannot rely on internal military investigations by the US, Nato and Afghan forces.”
She clarified that the International Humanitarian Fact-Finding Commission (IHFFC) was “the only permanent body set up specifically to investigate violations on an international humanitarian law”.
“We ask signatory states to activate the commission to establish the truth and to reassert the protected status of hospitals in conflicts,” she added.
MSF says the co-ordinates of the hospital were well-known and its bombing could not have been a mistake.
The charity – winner of the 1999 Nobel Peace Prize – has said it is proceeding from the assumption that the attack was a war crime.