As Tony Abbott prepares to farewell military personnel to the Middle East, Iraq has warned that Syria must be part of the plan to destroy Islamic State.

Iraq’s ambassador to Australia believes Islamic State cannot be eliminated without international forces going into Syria.

The ambassador’s comments came as Prime Minister Tony Abbott, who said at the weekend there was no plan to take action in Syria, confirmed Australia’s direct combat role in Iraq would be limited to air strikes.

Mr Abbott will farewell RAAF members heading to the Middle East on Thursday, pausing his week-long visit to Arnhem Land.

Iraqi ambassador Mouayed Saleh said the mission to destroy Islamic State (IS, also known as ISIL) would not be easy because the terrorist organisation had become “deep rooted” in Iraq and Syria.

The Iraqi army had been gradually recapturing some of the IS-seized areas, but the key to destroying the extremists lay in Syria.

“In order to really eliminate (IS), you have to go in Syria and take care of their bases,” Mr Saleh told Sky News on Wednesday.

“It’s up to Australia and the other countries in the coalition to decide on that.”

Mr Abbott again ruled out any Australian ground troops in Iraq, despite a US military chief indicating this could be the next step.

The White House has insisted the fight against IS in Iraq will not involve US ground troops, only air strikes and military advisers to the Iraqi army and Kurdish Peshmerga.

But the chairman of the joint chiefs of staff, General Martin Dempsey, told a Senate hearing in Washington the advisers could be drawn into combat.

General Dempsey said if he came to the conclusion that coalition force advisers should accompany Iraqi troops on attacks on specific targets, he would recommend it to President Barack Obama.

Mr Abbott said the only Australian combat operations inside Iraq would be air combat operations.

“But part of our force does include a contingent of (200) special forces and they will be available to act as military advisers to the Iraqi security forces and Peshmerga,” he said.

Asked whether the special forces could go to the front line, Mr Abbott said: “If we have military advisers with the headquarters of Iraqi security forces and Peshmerga, they will be moving around with those unit headquarters.

“Our troops will certainly be armed and if they are fired upon they will be entitled to respond.”

The Australian contingent will include 600 troops and up to eight Super Hornet jets.

Meanwhile, RAAF aircraft have delivered a fourth shipment of arms to Erbil in northern Iraq.

A RAAF C-17A Globemaster flying from Tirana, Albania, completed the delivery to Erbil on Tuesday without incident, a Defence spokesman said.

Opposition Leader Bill Shorten met Muslim leaders in Sydney on Wednesday, who he said were “committed to Australia”.