A commitment of additional Australian troops to Iraq, likely to number in the hundreds, is imminent, sources have told the ABC.

Australia already has 200 special forces personnel in Iraq and it is understood the extra troops will be part of a joint mission with New Zealand to train Iraqi soldiers.

New Zealand prime minister John Key announced on Tuesday the deployment of 143 personnel to Iraq.

This morning, the Chief of the Australian Defence Force Air Chief Marshall Mark Binskin said Australia had not yet decided the nature of a further commitment.

"I and my New Zealand counterpart have worked very closely on developing options that were put to both governments," he told a Senate committee.

"The Government of Australia is yet to make a final decision."

Prime Minister Tony Abbott said there had been talks about an additional contribution from Australia.

"It's been well known for some time that we have been talking to our allies, we've been talking to the Iraqis about what more we could do to assist the Iraqis to reclaim their own country," he said.

"We are talking to our friends and allies.

"Obviously that includes the New Zealanders about what more we can do to help the Iraqi security forces and I'll have more to say in the next day or so."

In an address yesterday to the New Zealand parliament, Mr Key told his countrymen the deployment would be alongside Australian soldiers.

"This is likely to be a joint training mission with Australia, although it won't be badged an ANZAC force," he said.

Officially, the Australian Government has remained tight lipped.

However, Mr Key's announcement of extra troops would not have come as any surprise to the Government or Defence officials.

My Key's speech to Parliament was widely flagged as long as two weeks ago, and the New Zealand defence minister has been in Australia in recent days.

The ABC understands Mr Key phoned Mr Abbott on Monday night ahead of his announcement.

Defence Minister Kevin Andrews welcomed the New Zealand decision during Tuesday's Question Time.

Asked by the ABC if it would mean sending additional Australian troops, a spokesman for Mr Andrews said that Australia's commitment was "always under active consideration".

"Australia continues to talk to Iraq, the US and our other partners about what we can do to support the Iraqi government," the spokesman said.

"No decisions have been taken by the Government to deploy additional personnel."

But the cat may have been out of the bag long before New Zealand's announcement.

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In early February, after visiting Australia for the Australia-UK ministerial talks, British foreign secretary Phillip Hammond flew on to New Zealand.

Asked there by reporters about whether the Kiwis should send troops, the New Zealand Herald reported that Mr Hammond said Australia was keen to have New Zealanders join a training mission.

"They are looking at now engaging a training mission – which they are committed to do – which would need another 400 people," he reportedly said.

"They are desperately keen that a contribution to that 400 is coming from New Zealand."

The United States welcomed New Zealand's decision to send troops to Iraq.

"As one of our partners in the coalition, New Zealand has already provided substantial humanitarian assistance to Iraq and Syria," state department spokeswoman Jen Psaki said.

"We value the contributions and efforts of all partners in the mission as we work together on a multifaceted and long-term strategy to degrade and defeat ISIL."

Mr Key's announcement makes for awkward political timing for Mr Abbott.

Mr Abbott is due to make his first visit to New Zealand as Prime Minister on Friday.

It would be highly unusual for the Prime Minister to commit to sending troops abroad while himself on foreign soil.

If, like Mr Key, he is to make an announcement in Parliament, he has two sitting days remaining.