US President Obama called the head of Doctors Without Borders to offer condolences for the airstrike on the group's hospital. While the aid group wants a war crimes inquiry, the White House called the attack an accident.
US President Barack Obama promised a "transparent, thorough and objective" investigation to the groups chief Joanne Liu, White House spokesman Josh Earnest said on Wednesday.
The weekend air strike on the hospital in the Afghan city of Kunduz killed 22 people, including patients and medical professionals working for the international charity organization Doctors Without Borders (MSF). Washington has since acknowledged that the US forces "mistakenly struck" the medical facility.
"When we make a mistake we own up to it," Earnest told reporters on Wednesday. "We apologize and we make changes to be sure it won't occur again in the future."
Commenting on the air strike, the spokesman said that "there is no evidence that ... I've seen or that anybody else has presented that indicate that this was anything other than a terrible, tragic accident."
After talking to Obama, Joanne Liu reiterated the group's request for an independent probe to establish "what happened in Kunduz, how it happened, and why it happened."
Earlier on Wednesday, Liu stated that "we cannot rely on an internal [US] military investigation." The medical charity said it deems the US attack to possibly have been a war crime.
MSF also urged Obama to consent to an inquiry by a Swiss-based humanitarian body, the International Humanitarian Fact-Finding Commission (IHFFC), that was never invoked before.
Obama has also called the president of Afghanistan, Ashraf Ghani, to convey condolences for the victims of the Kunduz airstrike and pledge continued cooperation with his government, the White House said.
Kabul 'committed' to investigation
Responding to the MSF push for the fact-finding mission, Ghani's office said that government "will fully cooperate with the investigation through appropriate channels agreed upon by our partners" in the NATO Resolute Support mission.
Taliban militants first seized Kunduz last week, but were soon pushed back by the Afghan security forces backed by NATO air strikes. The government is now controlling most key points in the city, with insurgents setting up pockets of resistance in certain areas.
dj/sms (AP, Reuters, dpa)