US President Barack Obama has apologised to medical charity Médecins sans Frontières (Doctors Without Borders) following the bombing of a hospital in Afghanistan, the White House said.
The air strike at the MSF-run hospital in Kunduz killed 22 people, including three children.
The United States military has expressed "deepest condolences" to the civilians killed in an airstrike on a hospital in Kunduz, Afghanistan.
Pentagon official General John Campbell says that Afghan forces said they were taking fire from enemy positions and asked for air support.
General Campbell said the Taliban for "fighting within the city" that put civilians in harm's way, and US advice and air support would still be available for Afghan forces despite the tragedy.
"We have now learned that on 3rd October Afghan forces advised that they were taking fire from enemy positions and asked for air support from U.S. forces," Campbell said. "An air strike was then called to eliminate the Taliban threat and several civilians were accidentally struck."
He did not specify if the air strike had struck the Medecins Sans Frontieres hospital.
The deadly air strike on Saturday killed 22 people when it hit the medical facility.
Investigations by Nato and Afghan forces will be carried out, Campbell said.
There could be a long wait for answers as to how and why Kunduz hospital ended up being on the receiving end of US air strikes.
Medical charity worker relates how he and colleagues tried to save patients and staff following devastating air strike.