Australian DJs in Kate Middleton Prank -- Ducking for Cover

The two Australian DJs at the center of the Kate Middleton hospital prank have gone RADIO SILENT since news broke that the nurse at the hospital committed suicide ... TMZ has learned.

The DJs are under serious fire after pulling off a stunt where they pretended to be the Queen of England (fake voice and all) and duped nurse Jacintha Saldanha into connecting them to the people treating Middleton, who revealed details about Kate's condition.

Saldanha's body was discovered early this morning ... and cops believe it's an obvious suicide.

TMZ called the Australian radio station where the DJs work ... and were told by the executive producer that the DJs will NOT be taking any calls, period.

The E.P. explained ... the DJs have been "ordered" not to speak to the media. It's unclear who issued the order.

The producer added, "I advise you to stop trying to call them."