KABUL - Afghan forces asked for a US airstrike on a hospital in Kunduz that killed 22 people, the top Nato commander in the country said Monday, after medical charity MSF branded the incident a war crime.

General John Campbell’s statement marks a departure from previous US military claims that the strike was carried out Saturday to protect American special forces who came under enemy fire in the northern Afghan city.

His remarks are unlikely to assuage global outrage over claims by MSF that the hospital was repeatedly bombarded for more than an hour despite their frantic calls to military officials in Kabul and Washington.

“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 US air forces,” Campbell told reporters. “An airstrike was then called to eliminate the Taliban threat and several civilians were accidentally struck.”

There was no immediate reaction from Afghan officials but they have previously claimed that insurgents were using the hospital as a position to target soldiers and civilians.

Campbell’s statement comes after pressure mounted on Washington to come clean over the strike, which caused patients to be burned to death in their beds and reduced the hospital to smouldering rubble.

Doctors Without Borders (MSF) said Sunday it has closed the trauma centre, seen as a lifeline in a war-battered region with scant medical care, and demanded an independent probe into the devastating air raid.

“Under the clear presumption that a war crime has been committed, MSF demands that a full and transparent investigation into the event be conducted by an independent international body,” MSF general director Christopher Stokes said.

Stokes also hit out at claims by Afghan officials that militants were inside the hospital. “These statements imply that Afghan and US forces working together decided to raze to the ground a fully functioning hospital with more than 180 staff and patients inside because they claim that members of the Taliban were present,” he said.

“This amounts to an admission of a war crime. This utterly contradicts the initial attempts of the US government to minimise the attack as ‘collateral damage’.”

The group said Afghan and coalition troops were fully aware of the exact location of the hospital, having been given GPS coordinates of the facility which had been providing care for four years.It added that the main building housing the intensive care unit and emergency rooms was “repeatedly, very precisely” hit almost every 15 minutes for more than an hour.

US Defense Secretary Ashton Carter expressed sadness over the “tragic loss of life” and repeated President Barack Obama’s promise of a full and transparent investigation. However MSF’s Stokes stressed the need for an independent probe, saying “an internal investigation by a party to the conflict would be wholly insufficient”.

The air raid came five days after Taliban fighters seized control of the strategic northern city of Kunduz, in their most spectacular victory since being toppled from power by a US-led coalition in 2001.

Residents told AFP Monday that the clashes appeared to have subsided. Afghan forces, backed up by their Nato allies, claim to have wrestled back control of the city, where decomposing bodies still littered the streets. At least 60 people are known to have died and 400 to have been wounded in the past week’s fighting.

Saturday’s raid left the hospital’s main building completely gutted. Some of the bodies of those trapped inside were charred beyond recognition. The dead included 12 MSF staff and 10 patients, among them three children.

MSF’s withdrawal from Kunduz comes as the region grapples with a humanitarian crisis, with food and medicine shortages affecting thousands of civilians caught in the crossfire between government forces and insurgents.

The hospital was the only medical facility in the whole northeastern region of Afghanistan that can deal with major war injuries. Its closure, even temporarily, could have a devastating impact on local civilians.

Kate Stegeman, a spokeswoman for the charity, told AFP she could not confirm whether the trauma centre will reopen. The incident has renewed concerns about the use of US air strikes in Afghanistan, a deeply contentious issue in the 14-year campaign against Taliban insurgents.

UN rights chief Zeid Ra’ad Al Hussein has also called for a full and transparent probe, noting: “An air strike on a hospital may amount to a war crime.” Human Rights Watch also said the strike raises “grave concerns” about whether US forces took sufficient precautions to identify and avoid striking the facility.