He said he wanted the government to have the power to deny citizenship to anyone who leaves Australia and joins overseas wars, like the dozens of Australians who have joined Islamic State. Prime Minister Tony Abbott: "What happens if they get off? That's the problem." Credit:Andrew Meares "What happens if they get off? That's the problem," he said on Friday. "We all know there are evidentiary issues with prosecutions of people for offences abroad... "Now, I don't want terrorists in our country. Full stop.

And if someone leaves our country tojoin a terrorist army abroad, I

don't want them back."

The government is relying on the recommendations of the former national security monitor Bret Walker SC who in March 2014 said: "Consideration should be given to the introduction of a power for the Minister for Immigration to revoke the citizenship of Australians, where to do so would not render them stateless, where the Minister is satisfied that the person has engaged in acts prejudicial to Australia's security and it is not in Australia's interest for the person to remain in Australia." Mr Walker did not state in his recommendation that a conviction would be required first but he has subsequently said that it should have been obvious to the Prime Minister. "Surely the Prime Minister doesn't think that because I didn't mention it, it didn't apply," he told Fairfax Media. "How ridiculous. His position is indefensible and he should apologise." The report extensively cites the similar laws in Britain but constitutional lawyer Professor Greg Craven has pointed out that unlike Australia, the United Kingdom does not have a written constitution enshrining the separation of powers. Labor's Mr Dreyfus says suspected terrorists should be convicted first.

"We don't want to see a ministerial whim, as I've called it, we think, as does the national security, the former national security legislation monitor, that there should be a conviction," the shadow attorney-general told the ABC on Thursday. Mr Abbott, who has staged a comeback in the polls after focusing heavily on national security this year, said this was tantamount to Labor "rolling out the red carpet for terrorists". "The tragedy is that there's well over a hundred Australians who've gone to fight with terrorist armies in the Middle East. The government wants to keep them out, I regret to say the Labor Party wants to bring them back," the Prime Minister said in Cairns on Friday. Mr Abbott is confident that the legislation, due to be released next week, will stand up to any constitutional test. Cabinet Minister and former Liberal leader Malcolm Turnbull has internally voiced serious concerns about it complying with the rule of law. He told the ABC there was no point in pretending the idea wouldn't involve a constitutional risk.

"Clearly if you have a minister making a decision that somebody has been guilty of some criminal offence, and then cancelling their citizenship without any court conviction or court decision, then there is going to be a constitutional issue," he said. "There is no question about that and there is no point pretending there won't be one." Mr Turnbull said he was working, as part of the government, to present a legally viable bill. "Clearly the government – and I am working very hard with the Immigration Minister and the Attorney-General and the Prime Minister providing a lot of input and assistance to ensure that the bill that is presented conforms to the constitution," he said. The Law Council of Australia has issued a statement expressing concern about the proposed legislation.

"The separation of powers means that a minister cannot exercise a judicial role to decide criminal guilt," Law Council president Mr Duncan McConnel said. Follow Latika Bourke on Facebook