The Australian Defence Force says no errors were made in a coalition air mission over West Mosul involving Australian super hornets that may have caused up to 18 civilian casualties on the ground.

Chief of Joint Operations, Air Marshal Mel Hupfeld, said any loss of civilian life was always regrettable and treated seriously.

“I can say from personal experience that the responsibility to take lethal action in wartime is a heavy burden to carry,” he told reporters in Canberra.

“Our pilots and decision makers involved in the targeting process do everything they can to avoid civilian casualties, but sometimes it is not possible.”

Local media in Iraq reported the deaths following a coalition air mission involving two Australian F/A-18 super hornets in June 2017 during the height of the battle for Mosul.

The ADF has confirmed that after Iraqi security forces on the ground spotted three enemy fighters in a building 70 metres away, and another four in a courtyard nearby, they requested support from the air.

Australian pilots were among those deployed in response. They struck both the building and the courtyard with around 226 kilograms of explosives.

“There was no specific intelligence to indicate civilians were present at the targeted site but given the urgent circumstances facing the Iraqi forces at the time, it was impossible to be certain,” Air Marshal Hupfeld said.

“This was a defensive response so the opportunity to do that surveillance in more detail was not available due to the direct threat to serious injury and imminent loss of life to the Iraqi security forces in the mission they were engaged with.”

It is now believed civilians may have been as close as 100m away from the strike zone in another building.

Air Marshal Hupfeld said if the defence personnel involved had that information at the time, they would not have fired but the mission did still comply with rules of engagement.

“We’re not blaming the Iraqi security forces for this event or this incident. We’re very cognisant of the risk of inflicting civilian casualties in a very intense complex war zone,” he said.

“Certainly the priority for defence, collective defence of the Iraqi security forces, has to be taken into account in proportion to the risk of collateral damage. We take all feasible precautions to minimise civilian casualties.”

Coalition forces were first aware of the deaths in January last year after they were reported on the Airwars website, which tracks international air campaigns and any credible allegations of civilian casualties.

An Australian investigation has since been unable to determine the exact number of deaths as a result of the June 2017 air strikes but based on population density it could be anywhere between six and 18 people.

Investigators have had no access to the ground in West Mosul where the strikes took place.

Their investigation was completed in December but could not identify whether the deaths were a direct result of Australian, or nearby coalition air strikes, or other factors.

“The action in Mosul was the most ferocious air campaign that we have seen in our generation. It is an unfortunate consequence of war that these civilian casualties have occurred,” Air Marshal Hupfeld said.