Police have been asked to investigate "thuggish" threats by the CFMEU boss to expose Australian Building and Construction Commission inspectors.
John Setka told a rally in Melbourne on Tuesday, that the union was going to expose all ABCC inspectors and make their children "ashamed of who their parents are".
"Let me give a dire warning to them ABCC inspectors, be careful what you do. You're out there to destroy our lives," Mr Setka said on Tuesday.
"We will lobby their neighbourhoods, we will tell them who lives in that house and what he does for a living, or she, and we will go to their local footy club, we will go to their local shopping centre, they will not be able to show their faces anywhere."
Federal Employment Minister Michaelia Cash told the Senate she had referred Mr Setka's comments to the Australian Federal Police and Victoria Police.
"A whole new low was reached even by Mr Setka's standards yesterday, when he targeted the kids of the ABCC inspectors threatening to go to their local footy clubs, their local shopping centres," she said in question time on Wednesday.
"Thuggish behaviour like this, it doesn't matter where it occurs, should never, ever be on display and should be condemned outright."
She said Mr Setka had shown he was "not a fit or proper person" to hold such a position, and she called on Labor to sever all political ties with the CFMEU.
The union told AAP the comments "were just hyperbole that you'd expect at any rally of this nature".
"It'd be ridiculous to extrapolate anything more from them," the spokesman said.
Prime Minister Malcolm Turnbull said the CFMEU threatened the rule of law and threatened public officials with violence.
"Where are the values? Where is the principle? Where is the rule of law from Labor?" Mr Turnbull said in parliament.
Federal Labor leader Bill Shorten dissociated the party from Mr Setka's comments, saying "that's not the way to advance your cause".
Labor frontbencher Anthony Albanese also said the police referral was "appropriate".
"The comments are offensive. I completely repudiate them," Mr Albanese told Adelaide radio 5AA.
The Master Builders Australia chief executive Denita Wawn said "this kind of bullying is the building union's stock in trade and occurs every day on the nation's building sites".
Victorian Trades Hall Council Secretary Luke Hilakari did not condemn the comments, instead saying ABCC inspectors make it "hard for union officials to save workers' lives".
"If you'd been to the funerals these blokes have, you'd be more concerned about the ABCC running around like the government's ideological attack dog and endangering lives, than some off-handed comments at a rally," Mr Hilakari said.
Victoria Police released a statement confirming it was aware of the comments and had referred the matter to Crime Command for assessment.
A police spokeswoman said they would consult with the AFP as part of the assessment.
