Chief of Joint Operations Air Marshal Mel Hupfeld said Australian Super Hornets "may have" killed an estimated six to 18 civilians at the height of the battle to defeat Islamic State in Mosul in 2017.

According to the ADF, Iraqi security forces requested help on June 13, 2017, after Islamic State fighters were spotted setting up positions in a built-up west Mosul neighbourhood. As part of the response from the US-led international coalition, two Australian Super Hornets dropped bombs on a building and a courtyard.

The ADF says its air crews hit the targets accurately and initial Australian assessments suggested there were no civilian casualties. But Airwars - a website that tracks civilian deaths in war - claimed civilians in a nearby building were killed.

The ADF says it was first alerted to the claims in January 2018 via the US-led coalition. This prompted investigations by both Australia and the international coalition, which found the claims were "credible".

Air Marshal Hupfeld stressed the strikes were conducted within Australia's strict rules of engagement, adding it was impossible to say exactly who was responsible, as international, Iraqi and Islamic State forces were also nearby.

"We do not definitively know how these people where killed," Air Marshal Hupfeld said.

Airwars suggests there were 34 people killed and a further 16 injured, but rates this information as "contested". The ADF says between six and 18 civilians were killed, based on an assessment of population density.

"Any loss of civilian life is highly regrettable," Air Marshal Hupfeld told reporters in Canberra on Thursday.

"The responsibility to take lethal action in wartime is a heavy burden to carry."

Air Marshal Hupfeld added the air strikes were carried out in an "intense and complex war zone".

"The action in Mosul was the most ferocious air campaign that we have seen in our generation."

Since 2014, the international coalition has conducted 32,397 strikes in Iraq and Syria, and estimates that about 1190 civilians have been "unintentionally" killed as a result.

"We continue to employ thorough and deliberate targeting and strike processes to minimise the impact of our operations on civilian populations and infrastructure," the international coalition said in its latest civilian casualty report, released on Friday morning.

"This process includes the thorough review and vetting of each target package prior to a strike, and another review after that strike."

Australia carried out 2750 bombing runs in Iraq and Syria between 2014 and 2017 as part of the coalition.

This is not the first time Australian airstrikes have been linked to civilian deaths. In early 2018, the ADF conceded it was probably responsible for the deaths of two adults and the wounding of two children in a 2017 Mosul airstrike.

Air Marshal Hupfeld's comments were timed to coincide with a regular update from the international coalition on civilian casualties in Iraq and Syria. The Defence chief said it was possible other Australian strikes could be investigated.

Defence Minister Christopher Pyne said Australian pilots would not be disciplined as they were acting "entirely within the rules of engagement and under the law of warfare".

"So there will be no discipline for the pilots involved, because they were doing exactly the job they were supposed to do," he told The Today program on Channel Nine on Friday morning.

"It was tremendously upsetting civilians were killed and we can't be sure it was Australians, but in the fullness of transparency, we are prepared to say we could have been responsible."