The ABC says its Sydney offices were raided by the Australian Federal Police over a series of 2017 stories known as The Afghan Files.
Investigative journalists Dan Oakes and Sam Clark reported allegations of unlawful killings and misconduct by Australian special forces in Afghanistan.
"The search warrant names Mr Oakes, Mr Clark and ABC's director of News Gaven Morris," reports the ABC.
This is the second time in two days that police have executed search warrants against journalists. Yesterday a News Corp journalist's home was raided.
ABC investigative reporter Elise Worthington tweeted today: "A disturbing time to be an investigative journalist in Australia."
Marcus Strom, federal president of the MEAA, the union for journalists, said: "This is just outrageous. Police raiding journalists is becoming normalised. IT has to stop."
According to John Lyons, ABC Head of Investigative Journalism, ABC lawyers told the Police: "We waive no rights, and reserve right to take injunction against the warrant."
The Police officers reportedly said: "We will be taking material with us. It will be sealed."
Lyons asks: "Is this the new normal?"
ABC managing director David Anderson says it is highly unusual for the national broadcaster to be raided.
"This is a serious development and raises legitimate concerns over freedom of the press and proper public scrutiny of national security and Defence matters," he says.
"The ABC stands by its journalists, will protect its sources and continue to report without fear or favour on national security and intelligence issues when there is a clear public interest."
The Australian Federal Police say no arrests are expected today.
"The search warrant relates to a referral received on 11 July 2017 from the Chief of the Defence Force and the then-Acting Secretary for Defence," Police say.
Yesterday Police raided the Canberra home of Australian journalist Annika Smethurst, looking for the source of a leak of confidential information.
Search warrants for Smethurst's home, mobile phone and computer were executed by the Australian Federal Police, which later confirmed an investigation into an alleged unauthorised disclosure of national security information.
The raid, described by News Corp Australia as "outrageous and heavy-handed:", follows an article in April 2018 about a proposal to give security services the power to snoop on the emails, bank accounts and text messages of Australians.
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