"We cannot rely on an internal military investigation," Doctors without Borders chief Joanne Liu told reporters, insisting that an "international humanitarian fact-finding commission" should probe the attack.
"This was not just an attack on our hospital, it was an attack on the Geneva Conventions," Liu said.
"This cannot be tolerated."
![Doctors Without Borders](http://img.astroawani.com/2015-10/61444215110_freesize.jpg)
Liu (centre) gestures as she speaks between MSF Switzerland general director Bruno Jochum (right) and MSF lead counsel Françoise Saulnier (left) during a press conference in Geneva on Oct 7, 2015. - AFP Photo/Fabrice Coffrini
Her comments came after commanding General John Campbell on Tuesday acknowledged that Saturday's air strike in Kunduz, which killed 22 people, including 12 MSF staff, had been a tragic error.
Such a fact-finding commission called for by MSF is an independent mechanism created under international law, but which has never before been used, the charity said.
It would simply establish the facts and would not determine criminal accountability.
![Kunduz, Doctors Without Borders, MSF](http://img.astroawani.com/2015-10/71444214575_freesize.jpg)
This handout photograph released by MSF on Oct 7, 2015, shows medical personnel as they treat wounded colleagues and patients in a hospital in Kunduz on Oct 3, 2015, in the aftermath of an airstrike on the facility in the northern Afghan city. - AFP Photo/MSF
MSF has branded the strikes a war crime, and has pulled out of Kunduz in the aftermath of the attack.
Three investigations have already been opened into the incident, one by the Americans, one by the Afghans and one by NATO.