Medecins Sans Frontieres (MSF) has said it is “disgusted” by Afghan government justifications for the air strikes on a hospital in the city of Kunduz, which left 22 people dead, calling it a “war crime”.

The strikes by US-led Nato forces lasted for more than an hour from 02:00 local time on Saturday killed 12 MSF staff and ten patients, including three children. Dozens more were injured and the hospital was left severely damaged an non-operational.

Following the strike, the Afghan defence ministry claimed that “armed terrorists” were using the hospital “as a position to target Afghan forces and civilians”.

However, MSF said “not a single member of our staff reported any fighting inside Kunduz hospital compound prior to US airstrikes Saturday morning”.

In a statement, MSF General Director Christopher Stokes said:

“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. Relying only on an internal investigation by a party to the conflict would be wholly insufficient.

“Not a single member of our staff reported any fighting inside the MSF hospital compound prior to the US airstrike on Saturday morning. The hospital was full of MSF staff, patients and their caretakers. It is 12 MSF staff members and ten patients, including three children, who were killed in the attack.

“We reiterate that the main hospital building, where medical personnel were caring for patients, was repeatedly and very precisely hit during each aerial raid, while the rest of the compound was left mostly untouched. We condemn this attack, which constitutes a grave violation of International Humanitarian Law.”

UN High Commissioner for Human Rights Zeid Ra’ad Al Hussein has called for a swift, full and transparent investigation into the air strikes on the MSF hospital in Kunduz killing. He said:

“This event is utterly tragic, inexcusable, and possibly even criminal…International and Afghan military planners have an obligation to respect and protect civilians at all times, and medical facilities and personnel are the object of a special protection. These obligations apply no matter whose air force is involved, and irrespective of the location.”

The air strike on the hospital was one of a number of strikes on areas of Kunduz by US-led Nato forces in support of the Afghan army as they try to retake the city from the Taliban.