Forensic officers are continuing to comb the Sydney homes of the remaining suspects associated with an alleged terrorist plot to bring down an aircraft.
A 50-year-old man arrested over the plot has been released without charge, but three other men remain behind bars.
Police have until Sunday evening to either charge or release the men.
Opposition legal-affairs spokesman Mark Dreyfus has told the ABC additional security measures at airports across the country will remain in place for as long as necessary.
