Prime Minister Tony Abbott talks to troops.

Tony Abbott meets Australian troops at Al Minhad Air Base in the United Arab Emirates on Thursday. Photo: ADF

Prime Minister Tony Abbott has vowed that Australia will continue flying humanitarian missions over Mount Sinjar in northern Iraq until safety can be guaranteed for the thousands of Yazidi refugees hiding in the barren region.

As the prospects of an international mission to rescue the stranded refugees appeared to fall, Australian forces carried out their first airdrop of food and water from a C-130 transport plane on Thursday morning Australian time.

ADF Iraq aid drop.

An Australian C-130 transport plane has been dropping food and water to thousands of Yazidi refugees stranded in barren mountainous areas in northern Iraq.

Mr Abbott paid a snap visit to the Al Minhad Air Base in the Middle East where the troops are based and thanked them for ''putting forward the long, strong arm of Australia to help protect those people who are at the mercy of … the murderous hordes of the Islamic State movement''.

The Prime Minister said he expected the airdrops to continue ''over quite a few nights to come'' but said it was a chance to do something ''unambiguously good''.

''We're not trying to change a regime, we're not trying to establish democracy, [but] when something is clearly right and proper and good … then we in Australia try to do what we can to help.''

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Reportedly several thousand refugees, mostly from the minority Yazidi sect, remain holed up in the mountains, though this is a fraction of the tens of thousands previously believed to be hiding in the harsh, dry area.

The Pentagon announced on Thursday morning that air strikes against Islamic State militants and the efforts of Kurdish Pershmerga fighters, seemed to have allowed many of the refugees to flee the mountain area to relative safety and those that remained were in reasonable health. The Pentagon said a small US team had assessed the situation on Mount Sinjar and ''an evacuation mission is far less likely''.

The first Australian airdrop delivered 10 pallets of supplies including 150 boxes of high-energy biscuits and 340 boxes of bottled water, which is enough to sustain 3700 people for 24 hours.

The government has said that Iraqis and Syrians are eligible for 4000 existing special humanitarian resettlement places from overseas each year. These are part of the overall 13,750 humanitarian places the Abbott government offers annually.

The Greens will use the return of Parliament in a fortnight to push for the number of resettlement places to be restored to the 20,000 a year that existed under the previous Labor government.

''If the Prime Minister is serious about a humanitarian response, he would create extra places,'' Greens senator Sarah Hanson-Young said. ''One of the first things he did when he became Prime Minister was to cut the number of refugee places for Australia by almost a third.''

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