The Abbott government is considering toughening national security laws to curb the threat posed by Australians fighting abroad with extremist groups such as the Islamic State of Iraq and the Levant.
Prime Minister Tony Abbott vowed on Friday to ''do our damnedest to ensure'' that Australians fighting with extremist groups abroad cannot come home or will be detained if they do.
Also on Friday, the government announced that Australia had sent a ''small Australian defence force liaison element'' to help protect diplomats at the Australian embassy in Baghdad as fears grew about the chaos and violence gripping Iraq. Fairfax Media understands the defence team of about six to eight security specialists - including SAS members - were deployed to assess the embassy's security and make evacuation plans, including by liaison with the US embassy.
Mr Abbott, meanwhile, vowed firm action against Australians - believed to number up to 100 - who are fighting in Syria and Iraq with extremist groups.
''The important thing … is to ensure that as far as is humanly possible they don't come back into our country and if they do come back into our country they are taken into detention because what we can't have is trained killers - who hate our way of life, who hate us - making mischief with the potential to cause mayhem in our country. We just can't have that,'' Mr Abbott told radio 2GB.
Legal experts questioned this, saying an act of Parliament would be required before people's citizenship could be revoked, and preventative detention of people who posed a threat was only possible for 14 days under current laws.
But a spokeswoman for the Prime Minister later told Fairfax Media that under current laws, control orders could be used to ''monitor and limit their movement, association and communication''.
The spokeswoman also noted that a recent report by the Independent National Security Legislation Monitor, Bret Walker, called on the government to consider laws to revoke such people's citizenship - if they were dual citizens and therefore would not be rendered stateless.
''As [Immigration] Minister [Scott] Morrison indicated on 19 June, revocation of citizenship in such circumstances remains subject to continued discussion,'' the spokeswoman said.
Nicola McGarrity, a law lecturer at the University of NSW, said stripping people of their citizenship would be a long and difficult process and would likely be subject to court challenges.
''You can't just revoke someone's citizenship and refuse to let them come back in,'' she said.
''Politically, passing an act of Parliament that would essentially render Australians potentially stateless would be unpalatable. There may be constitutional issues as well.''