The Australian Federal Police (AFP) is liaising with the Commonwealth Director of Public Prosecutions about whether charges should be laid over leaks from Federal Jobs Minister Michaelia Cash's office about raids on the Australian Workers Union.

Some journalists were tipped off and waiting when AFP officers raided union offices in Melbourne and Sydney last October to seize documents relating to donations made to Get Up and Labor candidates when Bill Shorten was head of the AWU.

Senator Cash initially denied her office had any involvement in the leak to the media but subsequently told a Senate committee her senior media adviser had confessed that he had tipped off the media before the raids.

The adviser has since resigned.

There has been a long-running police investigation into the leak from her office.

On Monday AWU national secretary Daniel Walton said it was "troubling but not surprising that the AFP have decided to refer their investigation to the Commonwealth prosecutor".

"Clearly the AFP have learned enough here to believe it warrants the attention of the prosecutor," Mr Walton said.

Senator Cash's office has been contacted for comment.

Labor's employment spokesman Brendan O'Connor called on Senator Cash to answer questions including whether she is a witness or under investigation.

Police are aiming to send material to the director of public prosecutions in the next two weeks.

It is not clear how long it would take for the DPP to decide whether charges should be laid.