Don't know it is too late, but I found a friendly fire event in Libya on 1 December 1941.
An Italian artillery unit equiped with captured British trucks was bombed by German Stuka while attacking British poistions at Bir Berraneb (west of Bir el Gobi) and lost half of his guns, an armoured vehicle and 40 dead, including eight officers, one of them Lt-Col Dissegna, its commander.
Source:
http://www.afrikakorps.org/batterievolanti.htm (in French)
40 dead is high for a "tactical" friendly fire bombing (not counting the carpet bombing used by the Allied, that were sometimes more bloody, especially in Normandy).