Washington, Oct 7 (IANS): Commander of US forces in Afghanistan John Campbell acknowledged on Tuesday a US airstrike "mistakenly" struck a hospital in Kunduz, Afghanistan, on Saturday that killed 22 civilians.

"A hospital was mistakenly struck. We would never intentionally target a protected medical facility," said Campbell at a congressional hearing here amid protests from Doctors Without Borders, an aid agency which runs the hospital hit by the US airstrike.

According to Xinhua, Campbell fell short of acknowledging the US responsibility on Monday during a Pentagon briefing by merely indicating that "several civilians were accidentally struck".

Shortly after his remarks on Monday, the aid agency called for an independent investigation into the incident despite pledges from the White House and the Pentagon to conduct transparent investigations.

"Their (US) description of the attack keeps changing - from collateral damage, to a tragic incident, to now attempting to pass responsibility to the Afghanistan government," said General Director Christopher Stokes of the aid agency in a statement issued on Monday. "With such constant discrepancies in the US and Afghan accounts of what happened, the need for a full transparent independent investigation is ever more critical."

Meanwhile, Campbell said on Tuesday that the decision to provide aerial support came after requests from Afghan forces engaged in a conflict with Taliban militants in Kunduz, Afghanistan, insisting the decision to provide the air support was a US decision made within the US chain of command.