The stunned radio hosts -- Michael Christian and Mel Greig -- have since stepped down from their show following the tragedy and have apologised for their action.
The paper quoted a 2Day FM spokeswoman who said an internal investigation found that "all procedures and protocols were adhered to."
However, no details of the investigation were released.
If it is found that the station breached a licence condition, then it could lose its right to broadcast, may be subject to tighter restrictions and possibly a hefty fine.
The paper refereed that under the probe the parent company Southern Cross Austereo could be forced to name the employees who approved the prank. The information has been till now been refused. Those who could face a inquiry are station content director Derek Bargwanna, station manager Jeremy Simpson, national content director Craig Bruce and metropolitan radio chief Guy Dobson. Both the DJs and producers Emily Mills and Ben Harlum.
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