Foreign minister Julie Bishop has urged relatives or friends to blow the whistle on anyone taking children abroad to undergo female genital mutilation.
The Australian Federal Police is investigating reports of a Brisbane girl being taken from her home to undergo genital mutilation in Africa.
Female genital mutilation is illegal in Australia, as is removing children to undergo the procedure.
But it is virtually impossible for authorities to step in without evidence of somebody's intentions, Ms Bishop says.
"If somebody just presents with a passport and they're heading off overseas and we have no evidence to provide us with any cause to prevent the person leaving, then of course that happens," she told Fairfax radio on Tuesday.
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"People are free to travel on an Australian passport if they have a valid passport."
Ms Bishop said it was vital that family members or friends who were in the know about such plans let authorities know.
"This equally applies to foreign terrorist fighters," she said.
"It's the families that we need to hear from if there are such matters occurring."
Relatives were the ones most likely to notice changes in behaviour or the beginning of radicalisation, Ms Bishop said.
"(Whether it's) a girl leaving for overseas for this brutal, barbaric practice, or whether it's people leaving for overseas to take up with terrorist organisations."
An AFP spokeswoman said they were unable to reveal details of the case at this stage.
They could not confirm reports from The Guardian Australia that the girl was believed to have travelled to Gambia with her father to undergo the procedure.
