A police investigation has been launched into allegations a Michaelia Cash staff member leaked information to the media about raids on AWU offices.
The Australian Federal Police has confirmed an investigation has been launched into allegations a Michaelia Cash staffer leaked information to media about raids on Australian Workers' Union offices.
"The AFP has commenced an investigation into the alleged unauthorised disclosure of information concerning recent search warrants executed in support of a Registered Organisations Commission investigation," the AFP said in a statement to SBS News.
"As this matter is under investigation, the AFP will be making no further comment."
The AFP carried out raids on the AWU's Sydney and Melbourne offices on Tuesday.
Attorney-General George Brandis, filling in for Ms Cash at a spillover Senate committee hearing in Canberra on Friday, claimed her office was informed the previous night that police were looking into the matter.
Citing correspondence from the AFP, Senator Brandis said as the events were under investigation it would not be appropriate to discuss it any further.
"Neither I nor any officer who may be called before the committee this morning will be accepting any questions in relation to that matter at the request of the Australian Federal Police," he told Senators.
Senator Cash had a longstanding commitment in Perth on Friday and was unable to attend the hearing, the attorney said.
The presence of a news crew outside the Sydney office on Tuesday triggered Senator Cash to be questioned at a Senate hearing about whether or not her office had leaked information to the media.
Senator Cash told the committee on Wednesday on five occasions neither she nor her office had anything to do the media tipoff.
She also said she personally told the prime minister she had not been the person who leaked the information.
On Wednesday evening she announced her senior media adviser had resigned after he revealed he had informed journalists of the raids on the AWU's Sydney and Melbourne offices.
Labor says Senator Cash should resign or be sacked.
- with AAP