Prime Minister Tony Abbott has confirmed Australian planes will join humanitarian airdrops in Iraq and did not rule out the possibility of greater military involvement.

Prime Minister Tony Abbott has confirmed Australian planes will join humanitarian airdrops in Iraq and did not rule out the possibility of greater military involvement.

Abbott, speaking in London after security talks, said Canberra was in discussions with international partners on how to protect displaced Iraqi civilians trapped on Mount Sinjar by gunmen of the so-called 'Islamic State'.

"Australian aircraft will shortly be joining the humanitarian airlift and airdrop to the Mount Sinjar region and we are consulting with our partners including the United States, including the United Kingdom, about what further assistance Australia can give," he said late Tuesday.

Last week, the United States launched an air campaign to break the siege of Mount Sinjar, bring humanitarian relief to the Yazidis and support Kurdish troops protecting their capital Arbil.

Asked whether Australia's efforts could include further military action by defense forces, Abbott said: "We certainly don't rule that out.

But he stressed that any involvement would be a humanitarian mission to protect those at risk from the "murderous hordes" of the 'Islamic State' militants.

"There is a world of difference between getting involved to prevent genocide and the kind of involvement that we've seen in recent years by western countries in the Middle East... and no one should conflate the two," he said.

Abbott said the timing of the Australian assistance on airdrops, likely to include the use of two aircraft stationed in the Middle East, was still being worked out.