Australia is talking with coalition partners about a possible boost to its involvement in Iraq, Prime Minister Tony Abbott says.

Opening a summit on countering violent extremism in Sydney, Mr Abbott said the Islamic State terror group could not be negotiated with, only fought.

“We are talking with our friends and partners about how the air strikes might be more effective and how the Iraqi forces might be better helped,” Mr Abbott said.

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US President Barack Obama has authorised up to 450 extra US personnel to deploy to Iraq to expand the American advise-and-assist mission at Taqaddum air base, as planning continues to retake the key city of Ramadi.

Australia is the second-largest single contributor to the fight against ISIL in Iraq, providing 300 trainers based in Taji, an air task group and special forces on a counter-terrorism advise-and-assist mission in western Anbar.

Chief of Joint Operations, Vice Admiral David Johnston, declined to say what his advice would be to the government about future force numbers.

“The (current) campaign is the right campaign,” he told reporters in Canberra on Thursday.

“That is what the Iraqi government wants.”

He admitted ISIL, or Daesh, forces remained a capable and determined enemy and were proving difficult to contain.

“We are still not at the point where we see Daesh in retreat,” he said.

The huge losses at the start of Daesh’s push across Iraq – which saw about 70,000 Iraqi military killed – were still resonating in terms of the national military’s leadership and willingness to fight.

While RAAF Hornet bombers have flown more than 600 sorties, on three-quarters of occasions they have returned without using any weapons, mainly due to Daesh choosing to embed their fighters with civilians.

The capturing of US vehicles by Daesh has also made targeting difficult.

To date, no Australian air strikes have resulted in civilian deaths.

It is understood a revised Australian plan could include more “spotters” to make these air strikes more effective.

The joint Australian-New Zealand training mission in Iraq is due to deliver its first Iraqi forces graduates at the end of the month. They will head into operations soon after.

Colonel Mark Galton, who is in charge of the Taji task group, said many of the Iraqis had entered the course with only “basic skills” but had taken to the training very well.

-AAP