Investigations into the friendly fire death of Sergeant Andrew Doiron are ongoing, but Canada's military says the public may never learn the results.

There are conflicting accounts of the March 6th incident in northern Iraq, in which Kurdish troops fired on Canadian special forces personnel at an observation post near the front line.

Canadian defence officials dispute claims by Kurdish officials that the Canadians showed up unannounced and used an Arabic password.

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Navy Captain Paul Forget says one investigation is being conducted by the military's criminal investigation service and another by the special forces, but he adds the reports could end up as classified information.

The U.S.-led coalition is also conducting an investigation.

Two soldiers wounded by the Kurdish fighters have returned to duty in northern Iraq while a third is still recovering at a Canadian hospital.

Meantime, Canadian warplanes have attacked two more Islamic State targets in northern Iraq.

The military says CF-18s bombed fighting positions and construction equipment east of Mosul on Friday, and attacked a bomb-making factory near Kirkuk on Thursday.