The union movement has vowed to fight the Morrison government's proposed laws which would make deregistering industrial bodies simpler.
Industrial Relations Minister Christian Porter says the peak construction and mining union, the CFMMEU, should be deregistered and is prioritising laws that could help make that happen.
The minister - also the attorney-general - told The Australian Financial Review deregistering the CFMMEU was the best way to grapple with its "unlawful behaviour".
"The ultimate sanction that you have to have against an unlawful organisation is to fairly say that 'your unlawfulness means that you can't enjoy all of the rights and benefits of lawful registration'," he said.
"Ultimately, here, the appropriate sanction is to deregister an organisation like the CFMEU."
Mr Porter said the Ensuring Integrity Bill would make deregistering such unions easier.
But Australian Council of Trade Unions president Michele O'Neil said the laws were an attack against basic democratic freedoms.
"Unions are democratic organisations and attacking them hurts all working people," she said in a statement on Friday.
"This law will undermine workplace safety, increase wage and superannuation theft and make it harder for workers to get pay increases and be represented when they need help.
"The ACTU and the entire union movement will continue to oppose this legislation and fight against this attack on the rights of all Australians."
The bill was introduced to parliament in 2017 but suffered a blow last year when the coalition couldn't rally enough support among the Senate crossbench.
In the new parliament, the coalition will need the support of at least four crossbench senators to pass the bill.
The CFMMEU was on Friday fined $100,000 after two union officials acted improperly when attempting to enter two Melbourne worksites in 2014.
The minister's comments also come amid an ongoing controversy involving Victorian construction union boss John Setka.
Mr Setka's membership of the Labor Party has been suspended, pending a move to expel him at a national executive meeting on July 5, over accusations he told colleagues anti-family violence campaigner Rosie Batty's advocacy has led to men having fewer rights.
The Victorian secretary of the CFMMEU has rejected the allegations.
Though Mr Porter hasn't linked his views on deregistering the CFMMEU to Mr Setka, Queensland Labor senator Anthony Chisholm said the union shouldn't be penalised for an individual's behaviour.
"I don't think the membership of the CFMMEU should be punished for the actions of one person," Senator Chisholm told Sky News.
"There's a workforce out there that need representation from a strong union."
The ACTU and more than a dozen individual unions, including the three biggest in the country, have called on Mr Setka to step aside.
He has the backing of the national tier of the CFMMEU, but his Victorian deputy Shaun Reardon quit the post on Thursday over the issue, citing "irreconcilable differences".
