SYDNEY - Foreign Minister Julie Bishop Thursday said she was deeply concerned about 150 Australians learning the "terrorist trade" fighting alongside Sunni militants in Iraq and Syria.
The country's top diplomat was briefed by her intelligence analysts this week on the number of Australians, some dual citizens, taking up arms alongside rebel groups.
"It is extraordinary. There are about 150 Australians who have been or are still fighting with opposition groups in Syria and beyond," she told ABC radio.
"In Syria it seems that over a period of time they have moved from supporting the more moderate opposition groups to the more extreme and that includes this brutal extremist group, ISIS."
The Islamic State of Iraq and the Levant (ISIL, also known as ISIS) has crossed the border from Syria into northern Iraq and taken over key cities. It is now within striking distance of the capital Baghdad.
Bishop said she was "deeply concerned" about the threat the Australian fighters could pose when they return home after associating with "such brutal people".
"We are concerned that Australians are working with them, they're becoming radicalised, learning the terrorist trade, and if they come back to Australia of course it poses a security threat," she said.
"We're doing what we can to identify them. I have cancelled a number of passports on the advice of our intelligence agencies."
One of those reportedly in Iraq with the ISIL is Khaled Sharrouf, who served almost four years in an Australian prison after pleading guilty over a 2005 conspiracy to attack Sydney.
He fled the country in February using his brother's passport in what Australian officials called "a fairly major breakdown" in border security.
Asked if Australia should support the regime of Nuri al-Maliki in Iraq, whose Shia-led administration is accused of fanning anti-Sunni sectarian violence, Bishop admitted it was "not a good government".
"It is the only government in place in Iraq at present," she said.
"And the problems between the Sunnis and the Shiites are exacerbated by his manner of excluding them from the government.
"He's (al-Maliki) now calling for national unity, but that's a start. We need to see a political solution because a military solution could be catastrophic," she added.