Aust troops playing vital role in Iraq: PM

Prime Minister Tony Abbott says Australian troops are making a substantial contribution in fighting Daesh, or IS, in Iraq.

He said the fight against the terrorist group in the Middle East directly affected Australian security.

"We are there, effectively, to defend Australia and obviously I want our troops to be as vigorous as possible," Mr Abbott told Fairfax radio in Melbourne on Wednesday.

Mr Abbott wouldn't be drawn on whether he believes Australians are being under utilised in Iraq, saying only that the nation's troops were making a substantial contribution as they help to disrupt and degrade IS, also known as Daesh.

"We cannot defend Iraq if its own government and its own citizens are not prepared to do likewise," the prime minister said.

"But we are prepared to work with the Iraqis, we are prepared to work with our coalition partners on what is a vital Australian national interest - to defeat the death cult and to end the inspiration that it is providing to terrorism right around the world, including in Australia."

Mr Abbott reiterated that Australian troops were on an advise and assist mission.

They are working with the Iraqi counter-terrorist service, helping to train others, co-ordinate air strikes and sometimes leading air strikes against the death cult inside Iraq.