It was probably too hard to bother with you. but they do have the power to stop question & detain you
http://www.austlii.edu.au/au/legis/cth/consol_reg/atsr2005457/
The Act gives Australian Protective Service and Australian Federal Police officers the power to:<?:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
<UL =disc>
<LI =Msonormal style="MARGIN: 0cm 0cm 0pt; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l0 level1 lfo1; tab-stops: list 36.0pt">request a person's name, address and reason for being in a place, or in the vicinity of a place, person or thing in respect of which the Protective Service has functions, where the officer reasonably suspects the person might have just committed, might be committing, or might be about to commit a prescribed offence, </LI>
<LI =Msonormal style="MARGIN: 0cm 0cm 0pt; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l0 level1 lfo1; tab-stops: list 36.0pt">stop and search a person the officer reasonably suspects has in their possession a thing that could be used to cause substantial damage to a place or death or serious harm to a person in respect of which the Protective Service has functions, and </LI>
<LI =Msonormal style="MARGIN: 0cm 0cm 0pt; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l0 level1 lfo1; tab-stops: list 36.0pt">seize a thing the officer is searching for or any other thing the officer reasonably suspects is likely to be used to cause death or serious harm to a person, or to a person who is in a place, or in the vicinity of a place, person or thing in respect of which the Protective Service has functions</LI>
<LI =Msonormal style="MARGIN: 0cm 0cm 0pt; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l0 level1 lfo1; tab-stops: list 36.0pt">any Licensed , Uniformed, Airport Security Guard can request a person's name, address and reason for being in a place, their ASIC card, and have the powers to detain said persons not complying with the act.</LI>