An air strike initiated after Australian forces discovered a network of hidden caves and bunkers in Iraq has killed as many as 100 Islamic State fighters.
The attack on a network of caves and tunnels near Kirkuk was carried out about a week ago after a RAAF Super Hornet crew spotted people moving along the side of a mountain and then disappearing.
In the latest official briefing on the operation held at defence headquarters in Canberra, Vice Admiral David Johnston described how the Super Hornet's weapons systems operator observed an Islamic State militant moving to what was later discovered to be "a large well-established and hidden network of caves and bunkers that were concealed in a hillside".
Investigations confirmed that the fighters were moving underground, and within 24 hours a coalition air strike was called in.
Forty-four targets were hit, backed up by a large-scale ground offensive by Kurdish forces.
The Kirkuk attack is just one of a number of successful missions flown by RAAF Super Hornets in the past few weeks.
An Australian strike crew also took command of an operation against a factory in Mosul used to make improvised explosive devices. The factory was severely damaged.
Audio: Update on Australian Defence Force role in combatting Islamic State (PM)
As well as offensive operations, Australian air crews have been involved in a continuing humanitarian mission around Mt Sinjar, along with weapons drops.
Vice Admiral Johnston said the coalition was confident the "advance of ISIL across Iraq has slowed".
"There is a momentum shift but it isn't consistent," he said.
Iraqi forces have had some success in the north and south of the country, but the western approaches to Baghdad remain fairly fragile
Islamic State: Australian-initiated air strike kills up to 100 militant fighters in cave complex near Kirkuk - ABC News (Australian Broadcasting Corporation)