Police demands for the fingerprints of two ABC journalists being investigated for publishing leaked documents have been described as "chilling" by the federal opposition.
Labor frontbencher Jason Clare said the reporters were being treated like criminals.
"That would send a chill down most journalists' spine," Mr Clare told Sky News on Tuesday.
"The government has said that journalists weren't meant to be the targets of these raids, but obviously that's not true.
"We shouldn't see journalists in Australia treated like criminal suspects, and that's what this looks like."
Dan Oakes and Sam Clark are facing Australian Federal Police scrutiny over their involvement in stories about Australia's special forces allegedly carrying out unlawful killings in Afghanistan.
Opposition Leader Anthony Albanese repeated calls for the government to rule out prosecuting the journalists.
"This is a real issue - press freedom is an essential component of our democracy - and the government should be defending press freedom," Mr Albanese told reporters in Perth.
A letter from the AFP to the journalists was emailed on April 1 - two months before officers raided the ABC's Sydney headquarters seeking leaked documents relating to the stories.
The ABC said the email stated the AFP was "requesting your consent to a forensic procedure being the copying of your finger and palm prints", with the two journalists being suspects in relation to three alleged offences.
The broadcaster's head of investigations John Lyons said the revelation proved the men were police targets as part of the investigation.
"I haven't ever heard of journalists being asked for fingerprints," he told ABC News.
"This quite shocks me because it's the sort of thing that if someone has burgled a house, people try to get fingerprints to find out who was the thief."
The revelation followed a report in the Sydney Morning Herald, which said the AFP had sought Oakes's travel details from Qantas.
The ABC's managing director David Anderson has asked for the investigation to be dropped and is pursuing legal action to declare the search warrant involved the raid invalid.
The ABC is also seeking a permanent injunction stopping the AFP accessing the electronic files removed from Ultimo on a sealed USB stick.
The parliamentary joint committee on intelligence and security has begun an inquiry into the impact of the exercise of law enforcement and intelligence powers on the freedom of the press.
Australian Associated Press