Besieged Sydney radio station 2Day FM could be forced to break its silence over the royal prank call, with the media watchdog confirming it will investigate the scandal.
The station could lose its right to broadcast if it is found by the Australian Communications and Media Authority (ACMA) to have breached a licence condition. It may also be subject to tighter restrictions and a hefty fine.
Parent company Southern Cross Austereo could be compelled to name the employees who approved the prank – something it has refused to do so far.
Among those who could be grilled by investigators are station content director Derek Bargwanna, station manager Jeremy Simpson, national content director Craig Bruce and metropolitan radio chief Guy Dobson. DJs Michael Christian and Mel Greig, and producers Emily Mills and Ben Harlum, are also expected to be questioned.
On Wednesday night, Austereo denied that Bargwanna or in-house lawyer Tania Petsinis approved the broadcast of the prank call.
An ACMA spokesman said the watchdog would investigate whether 2Day FM breached its licence conditions or the industry's code of practice.
It will examine whether the station breached standards of decency, invaded privacy or broke rules of consent.
In a statement, ACMA said it "will be seeking to expedite this investigation and does not propose making any further statement while its investigation is underway".
Jacintha Saldanha, the nurse who took the initial call, was found dead three days after she was duped by the prank. Last night, a 2Day FM spokeswoman said an internal investigation found that "all procedures and protocols were adhered to", though it has not released details of this investigation.
Southern Cross CEO Rhys Holleran claimed the station tried "at least five times" to get approval from the hospital at which Saldanha worked as a nurse.
The hospital denies being contacted by 2Day FM and the station has not released phone records to prove the calls were made.
On Wednesday, Fairfax Media revealed that all 2Day FM presenters, producers and content managers receive training about "decency and standards" every three months. The training includes advice "not to air any prank calls without permission".
In the face of continuing global media scrutiny, the company has gagged its employees. While Christian and Greig have borne the brunt of the criticism, the senior staff who approved the stunt have refused to identify themselves or explain their decision.