Classified blueprints of the new ASIO headquarters in Canberra have been stolen in a cyber hit believed to have been mounted by hackers in China.
has discovered the plans were taken in an operation targeting a contractor involved with building the site.
The stolen blueprints included the building's security and communications systems, its floor plan, and its server locations.
The cyber attack is one of the reasons completion of the new building has been delayed.
The program said China appeared to be the main suspect behind the cyber attack.
Four Corners also found the departments of Defence, Prime Minister and Cabinet, and Foreign Affairs and Trade had all been breached in sustained hacking operations.
Federal Attorney-General Mark Dreyfus has declined to say if the breach took place.
"There's a great deal of intelligence material, espionage-related material that we don't comment on," he said.
"The more that is disclosed about what's known about espionage activity in Australia or operational aspects in counter-intelligence, the more that our opponents, people who are engaging in espionage, will know about our capability and know about the methods that we have for detecting espionage or cyber threats."
The director of the Centre for Internet Safety, Alastair MacGibbon, says the Government should be more open about what has happened.
"There have been probably many breaches of Government agencies but we don't have a culture in this country of talking about it," he said.
Professor Des Ball from the Australian National University's Strategic and Defence Studies Centre has told the program the theft of the ASIO building's blueprints is particularly significant.
"Once you get those building plans you can start constructing your own wiring diagrams, where the linkages are through telephone connections, through wi-fi connections, which rooms are likely to be the ones that are used for sensitive conversations, how to surreptitiously put devices into the walls of those rooms," he said.