Terrorists fighting in overseas campaigns could return to Australia's shores due to loopholes in the anti-terror laws that were designed to keep them out.
Immigration Minister Peter Dutton introduced the laws to strip Australia's homegrown terrorists of their citizenship more than a year ago, but the Daily Telegraph reports many could slip through cracks in the law.
Intelligence experts are warning the law might not prevent more than 100 terrorists fighting with groups like the Islamic State from lawfully returning to Australia.
One loophole that could be exploited is the need for authorities to show an Australian terrorist holds citizenship with another country.
This would require the governments in countries such as Syria and Iraq to cooperate with Australian immigration department officials, but so far they have refused to assist.
Of the 100 Australian terrorists fighting in Syria and Iraq, only Khaled Sharrouf has been stripped of his citizenship because the Lebanese government accommodated Canberra's request.
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There are warnings many Islamic militants could return home as coalition forces smash the Islamic State and drive it from territory in Syria and Iraq.
There have already been as many as 40 fighters return home in the past three years after fighting for ISIS, the newspaper reports.
Another exploitable hole in the legislation concerns officially "declared terrorist organisations".
As the Islamic State is the only Declared Terrorist Origination as of May 2016.
Security officials warn the government that under the law it would not be able to show that other Islamic militant groups in Syria, such as Al-Nusra Front or Jabhat Fateah al-Sham, is a terrorist organisation.
That the laws are not retroactive is also of grave concern, meaning some of Australia's most notorious terrorists would be allowed back.
That means the Australian terrorists who tweeted photos holding bloody severed heads before the legislation came into effect would be able to re-enter the country, according to legal experts.
Newsbreak – March 3