The US commander in Afghanistan said Thursday that his forces would never intentionally target a hospital and that all requests from Afghan troops for air support are thoroughly vetted.

General John Campbell was testifying to US lawmakers five days after a US air strike on a Doctors Without Borders hospital in the disputed Afghan city of Kunduz that killed at least 22 staff and patients.

President Barack Obama has apologized to the medical aid agency but three investigations -- by the US military, by NATO and by Afghan officials -- are underway and the general would not be drawn on their progress.

But, asked about unconfirmed allegations that Afghan troops had called in the US strike because wounded Taliban fighters were being treated in the hospital, Campbell said that would not be a justification.

"A hospital is a protected facility. We would not target a hospital," he told the US House of Representatives Armed Services Committee in Washington.  

"When the Afghans call for fire, that's not an automatic response. Every day the Afghans ask me for close air support and we just don't go fire some place," he said.

"We go through a rigorous procedure to put aerial fires on the ground -- A US process, under the US authorities.

"So we've got to figure out what happened in that case but I don't want people to think that just because the Afghans call fire that there's automatic fire anywhere they want it, that's just not the case."

Asked whether the presence of Taliban fighters in a hospital could justify a strike, Campbell said simply: "No."

On Thursday, Doctors Without Borders said nine patients and 24 staff are still missing after the bombing of the hospital, bringing the potential total toll to more than 50 people.

The aid agency has demanded an independent inquiry.

Source: AFP