Speaking to 3AW, Malcolm Turnbull said former Liberal frontbencher Wyatt Roy's trip to Iraq was "stupid " and that he is "disappointed" by Mr Roy's behaviour.
Mr Roy, 26, a former assistant minister and Australia's youngest ever parliamentarian, said he was caught in a deadly IS attack on Peshmerga forces about three to four kilometers out of the Iraqi town of Sinjar, west of Mosul, last Thursday.
"I'm disappointed in Wyatt, he shouldn't have gone to Iraq. He was acting in defiance of government advice. It was very stupid," Mr Turnbull said.
"Australians should not go to those parts of the world," he said, adding that he would be giving some "very sage and stern advice" upon his return to Australia.
But in an editorial for The Australian newspaper, Mr Roy said his visit to Iraq was useful.
"The advantage of doing an unofficial trip is the low profile — instead of getting whisked around on a whistlestop tour, you can really take the time to get out on the ground," Mr Roy said.
Mr Roy insists despite being caught up in the deadly battle, he is glad to have taken part in the trip in a region in which he said he had a "longstanding interest". He said he was trying to learn more about the conflict, which he could not have done while in politics.
"So given a unique opportunity to access the liberated town of Sinjar, or Shingal as they call it in Kurdish, I took it, keen to see for myself the realities of Daesh’s brutality and the challenges for those remarkable people facing them down."
As a Liberal member representing the seat of Longman in 2014, Mr Roy called for Australia to double the intake of its humanitarian migrant program.
"While we might not have had much luck that day, I now carry a greater conviction that those of us blessed to live in the “lucky country” have a moral obligation and responsibility to respond to these outrages of humanity with an assertive internationalism, " he said.
The government must now come clean: Labor
Labor's Penny Wong called on Foreign Minister Julie Bishop to "come clean on what prior knowledge she had of Mr Roy’s trip."
Ms Wong asked Ms Bishop to "immediately clarify what knowledge it had of Mr Roy's travel to this (the Iraq-Syria) war zone and whether any assistance was requested or provided by the Australian Government".
She also questioned the legality of his trip, whether he'd be questioned buy authorities on his return to Australia and if his trip involved any taxpayer money.
"This seems a very unwise, and potentially dangerous act for a former member of Parliament, who should be expected to know better.
Taking a stab at Mr Roy's former Queensland colleague, Peter Dutton, Ms Wong added that: "War zones are not places for people to act out their boyhood fantasies."
Peter Dutton had previously said the fight against IS should be left to Australia's military, not "cowboys" who put themselves in harm's way and might lead to other Australians being forced to risk their lives to rescue them.
'This is not a Contiki tour'
Defence Industry Minister Christopher Pyne said Mr Roy is a good friend of his and he's glad he's safe and well.
"It is certainly not a tourist destination," Mr Pyne told the Nine Network.
Labor defence spokesman Richard Marles said it was a "massive lapse of judgement".
"We are talking about a war zone. This is not a Contiki tour," he told the Nine Network.
"This is profoundly stupid, profoundly selfish."
Bishop slams 'irresponsible' Wyatt Roy after near miss in Iraq war zone
Foreign Minister Julie Bishop says former Liberal frontbencher Wyatt Roy's trip to Iraq was "irresponsible" and "in defiance of government advice".
Five insurgents from IS - also known as Daesh - were reported to have been killed in the firefight, which Coalition forces ended with an airstrike.
"For about half an hour we were being attacked by Daesh terrorists who were somewhere between one kilometre and 500 meters away with 50-cal weapons and RPG fire and mortars," he told SBS from Erbil, the capital of the semi-autonomous region of Iraqi Kurdistan.
Peshmerga reinforcements arrived from Sinjar, who were able to push the IS fighters back, he said. Within half an hour, the confrontation ended with two coalition airstrikes on IS.
Mr Roy had travelled to Domez with British political consultant Samuel Coates and a translator.
In a statement, Ms Bishop said official Australian government advice to all Australians was "do not travel to Iraq".
"The government has also banned travel to the Iraqi city of Mosul, which is under ISIL control," she said.
"The government does not endorse or approve of Mr Roy's actions, and strongly urges other Australians to follow the official advice of 'do not travel to Iraq'."
On his reasoning for heading to Iraq, Mr Roy said he wanted to go because of his “long-standing interest” in the region, which had also been a “strong policy interest” during his time in Australian politics.
Ms Bishop said Mr Roy "did not seek nor did he receive assistance from the Australia government for his travel to Iraq".
"It is irresponsible for Wyatt Roy to travel to the front line of the conflict between ISIL and Kurdish forces in norther Iraq, in a region regarded as very high risk," she said in her statement.
"He has placed himself at risk of physical harm and capture, and acted in defiance of government advice."
As a Liberal member for Longman in 2014, he had called to double Australia’s humanitarian migrant intake in support of Yazidi and Christian minorities and others displaced by the Iraq and Syria crises.
The city and its surrounds were the site of an attack by Islamic State in 2014 that the United Nations says resulted in the killing and forced displacement of thousands of people from the Yazidi minority group.
“Of course the town that I visited, the town of Sinjar, is the effectively the homeland of the Yazidi people, these are remarkable people who are facing effectively genocide at the hands of the very evil forces of Daesh.”
