CANBERRA -- A political firestorm is building over Tuesday's federal police raids on the Australian Workers Union (AWU), with Labor Leader Bill Shorten saying they are nothing more than a "grubby" attempt by a "grubby" Prime Minister to smear him.
However, Malcolm Turnbull is standing firm, pinging Shorten for "questions to answer" over his actions while union leader.
The Australian Federal Police (AFP) raid for documents in Sydney and Melbourne relate to an investigation by the Registered Organisations Commission (ROC) covering the 2006 pre-politics period Shorten led the AWU.
It is looking into whether union rules were transgressed by a $100,000 start up donation made to activist group GetUp and by other donations to Labor candidates. The minister for workplace relations, Michaelia Cash referred the matter to the ROC after raising it in the Senate two months ago.
The AWU will today head to the Federal Court in an attempt to stop the documents being examined by the ROC.
"I am frankly appalled at the Turnbull government hitting a new low yesterday in their attempts to smear myself, Labor and unions," Shorten told reporters in Canberra.
He said he had the "greatest respect" for the AFP and the +30 officers who conducted the raids, but aimed at the commission which ordered them.
"What I don't respect is the regulator at the behest of the government was conducting a political witch hunt designed to throw mud in the hope that some will stick."
Unions, led by the ACTU, have described the raid as an "abuse of power," while shadow workplace relations minister Brendan O'Connor has questioned the police involvement in the matter.
There are also questions over the media being tipped off before the raids took place.
However, under questioning at senate estimates on Wednesday, Cash said neither she nor her office informed the media before the raids took place, but her office took calls to responds to it.
Asked specifically by Labor's Doug Cameron if any ministerial office staff informed the media before the raids commenced, she said "No, Absolutely. Senator Cameron, I watched it unfold on the television," she told the hearing.
"I have full faith in my staff Senator Cameron." Cameron asked "have you?" and she responded "yes".
The prime minister is undeterred and has defended the raids, accusing Labor of showing a lack of respect to the AFP in questioning the raids.
He insists the AFP are independent.
"The AWU has got questions to answer, Bill Shorten has questions to answer," Turnbull told reporters in Sutton in regional NSW.
"Why his union was making a $100,000 donation to GetUp, an organisation which I might say as opposed to most of the industries that employ members of the AWU.
"But those are questions for Mr Shorten to answer, and I want to say the hysterical attack by Brendan O'Connor on the integrity of the Australian Federal Police is a disgrace, and Bill Shorten should own that and apologise for that immediately."
Shorten said he survived what he called the "political smear fest" of the Royal Commission on Trade Union Corruption without an adverse finding and he's accused the government of desperation.
"Yet again, yesterday the government is wasting taxpayer money by a increasingly grubby effort by a grubby government and, quite frankly, a grubby prime minister who've been exposed as standing for nothing," he said.
"All they have left is try and damage the reputation of their opponents."