A man wearing an Afghan National Army uniform has opened fire on foreign troops at a training facility, causing casualties, an Afghan military spokesman has said.

"We are investigating but it appears that an Afghan army officer opened fire. Three of our officers have been injured, some (International Security Assistance Force) ISAF troops have also suffered casualties," General Mohammed Afzal Aman, the chief of staff for operations at the Afghan Ministry of Defence, told AFP on Tuesday.

ISAF said in a statement that it was investigating an "incident" at Camp Qargha, west of Kabul, involving Afghan and NATO troops.

"We can confirm that an incident occurred involving local Afghan and ISAF troops at Camp Qargha today in Kabul City, Afghanistan," the statement said.

"The camp, also known as the Kabul ANA Officer Academy, is an Afghan National Security Forces facility. We are in the process of assessing the situation."

Source: Al Jazeera and agencies