Jobs minister Michaelia Cash is holding out against calls for her to step down now that the Australian Federal Police (AFP) have referred to prosecutors its materials over her role in leaks about a controversial raid on union offices.

The Commonwealth Director of Public Prosecutions will have to decide if charges are in order.

Last October, the AFP raided Australian Workers Union offices in Sydney and Melbourne.  Reporters were already there waiting for the police, having been tipped off. 

Ms. Cash initially denied that her office was involved in the leaks.  But later that month, Buzzfeed news reported that Cash's then-senior media adviser - David De Garis - was the one who tipped off the media, and her resigned.  That spurred the AFP to set up its own investigation into the leak.

"It is troubling, but not surprising, that the Australian federal police have decided to refer their investigation to the commonwealth prosecutor," said Daniel Walton, national secretary of the Australian Workers Union.  "Clearly the AFP have learned enough here to believe it warrants the attention of the prosecutor," he added.

"Michaelia Cash should have resigned long ago," said Australian Council of Trade Unions secretary Sally McManus.