Afghan forces asked for U.S. air support while fighting the Taliban in Kunduz shortly before an air strike resulted in the deaths of civilians there, the American commander of international forces in Afghanistan said on Monday.

U.S. Army General John Campbell's comments fell short of squarely acknowledging U.S. responsibility for an air strike that killed 22 people in an Afghan hospital run by aid group Medecins Sans Frontieres (MSF) on Saturday.

"We have now learned that on October 3 Afghan forces advised that they were taking fire from enemy positions and asked for air support from U.S. forces," Campbell said in a briefing with reporters. "An air strike was then called to eliminate the Taliban threat, and several civilians were accidentally struck."

Campbell said U.S. forces were not under direct fire in the incident and the air strike had not been called on their behalf, contrary to previous statements from the U.S. military. He criticized the Taliban for fighting from within urban areas and putting civilians at risk.

"If errors were committed, we'll acknowledge them," Campbell said. "We'll hold those responsible accountable, and we'll take steps to ensure mistakes are not repeated."