Victoria's former CFMEU boss has been referred to police by the state's premier after he entered two government building sites to address workers.
Jacinta Allan said police had been contacted after John Setka spoke to about 700 workers at a Metro Tunnel project site on Thursday morning.
It comes after Setka addressed workers at Footscray Hospital, which is undergoing a $1.5 billion revamp, on Wednesday.
"There is no place for John Setka on these worksites," Ms Allan told reporters.
"He was on the sites unlawfully and that is why the matter has been referred to Victoria Police.
"In terms of who attends work sites, there are well-established processes here and it is the government's expectation that those building industry companies manage this process appropriately, which is clearly not what happened in these incidents over the past 24 hours."
Setka launched an expletive-laden criticism of the state and federal governments during his visit to the Melbourne hospital build site.
"People sort of asked why I resigned and I'm going to be honest with youse, f*****g Albo, and his f***ing bullshit," he told workers.
Setka, who quit in July after allegations that bikies and underworld figures had infiltrated the union, gave insight into how his resignation unfolded.
"They want a scalp you tell them I'll go," he told the crowd.
"I'll resign right now. I'll resign tonight.
"My job is to protect the union and its members.
"I'm going to be gone in a few months."
The Victorian government has asked construction giant Multiplex, which is managing the project, how the on-site rally unfolded.
A Multiplex spokesperson said the company did not authorise Setka to appear at Footscray Hospital and was investigating how he gained access.
The Fair Work Ombudsman said it was investigating allegations former CFMEU officials attended construction sites.
A Victoria Police spokesperson confirmed police received a verbal briefing from the police minister's office about "a pending referral regarding a former union official".
Federal Opposition Leader Peter Dutton said Setka had "stunning audacity" to enter a second worksite.
"John Setka's worked out as well that Anthony Albanese is a weak leader," Mr Dutton told reporters in Sydney.
"They (the CFMEU) trade in misery.
"They go onto building sites, which forces up the cost of building."
Victorian Opposition Leader John Pesutto said Setka was "making a mockery" of the government.
"Premier Jacinta Allan and John Setka have one thing in common - they both claim to run Victoria," he told reporters.
The Maritime Union of Australia will join other trade unions to help fund a High Court challenge after the CFMEU was placed into administration.
It said the government's decision was "unjustified, chaotic and reckless", could jeopardise progress on enterprise bargaining agreements and send a green light to "bad and abusive employers".
"We are also concerned by the near certainty that similar future legislation will be used by governments of either stripe against other militant blue-collar unions, including the MUA," it said.
"We have been on the receiving end of these calculated political and media smears in the past and will support our fellow members ... as they seek to clear their names and fight for the principles of natural justice, presumption of innocence, the rules of evidence and procedural fairness."
The embattled CFMEU had its construction and general divisions placed into administration after corruption allegations prompted the federal government to try to rein it in.
Laws to bolster this effort passed parliament in August and gave the relevant minister powers to intervene and slap life bans on CFMEU officials.
Mark Irving KC was appointed as administrator and the roles of more than 200 elected CFMEU officers were terminated.
