Australian refuelling and surveillance planes will today start flying over Iraq in support of the international coalition battling Islamic State (IS) militants, Prime Minister Tony Abbott says.

But Mr Abbott has told Parliament there is yet to be a decision made on when to commit Australian combat aircraft to the fight against what he says is an “apocalyptic death cult”.

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Australia last month sent 600 military personnel and eight F/A-18F Super Hornet fighter jets to the United Arab Emirates in preparation for joining the attack on IS targets in Iraq.

“We have not yet made a final decision to commit our forces to combat but Australian aircraft from today will start flying over Iraq in support of allied operations,” Mr Abbott told Question Time this afternoon.

“Ours are support operations, not strike missions.

“Australian air strikes await final clearances from the Iraqi government and a further decision by our own. But from today our refueller and our Wedgetail [surveillance aircraft] will operate over Iraq in support of US and other coalition aircraft.”

Opposition Leader Bill Shorten said the Defence Force has Labor’s support for the “humanitarian mission”.

“Labor’s taken a strong interest in ensuring that Australia meets its international legal and diplomatic obligations and in guaranteeing that the appropriate force protection measures are in place for Australians serving in the region,” Mr Shorten said.

“This is part of Australia’s responsibilities as a good international citizen as well as providing important legal protections for our Defence personnel.”

Earlier this week Foreign Affairs Minister Julie Bishop signalled a decision on whether or not to join combat missions against IS was imminent.

She said Australian forces would focus on the fight against IS militants in Iraq and not join US strikes in Syria.