The US Air Force has dropped criminal charges against two fighter pilots who mistakenly bombed Canadian troops in Afghanistan last year, killing four.

An American pilot who mistakenly bombed Canadian troops in Afghanistan last year, killing four of them, was under orders to hold fire when he dropped the bomb, a fellow airman testified.

A US pilot charged with involuntary manslaughter in the accidental bombing deaths of four Canadians in Afghanistan was under orders to hold fire when he dropped the bomb, a fellow airman testified yesterday.

Two US Air Force `weekend-warriors' are to face criminal charges for bombing Canadian soldiers in Afghanistan, killing four.