Tony Abbott says an Australian C-130 Hercules aircraft was not shot at by extremists while delivering humanitarian aid to northern Iraq.
The prime minister downplayed News Corp Australia reports the RAAF transport plane was attacked by Islamic State extremists as it dropped aid to the besieged town of Amerli.
"Yes they were flying into an active combat zone, so there may well have been fire in the area," Mr Abbott told Macquarie Radio on Tuesday.
"But I'm not advised that they came under direct fire themselves."
Reports the RAAF were fired on will only heighten concerns about its involvement in the humanitarian airdrops and in an international airlift of military equipment to Kurdish fighters.
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The prime minister said the government had carefully assessed the risks before agreeing to the air missions.
"Obviously flying into a war zone ... even humanitarian airdrops into combat zones are full of risks," he said.
"But the risks are reasonable given the importance of the mission they're flying."
Mr Abbott defended the West's involvement in Iraq, saying dire and dreadful measures were necessary to combat the "pure evil that we are now seeing".
"The atrocities that were committed by the Nazis, by the communists and others - they were ashamed of them, they tried to cover them up," he said.
"This mob by contrast, as soon as they've done something gruesome, ghastly and unspeakable, they're advertising it on the internet for all to see."
It was right to respond with "extreme force" to the IS "death cult", he said.
"These people do exult in death - they absolutely revel in killing," Mr Abbott said.
