The CFMEU has threatened to disrupt major Victorian government projects as tens of thousands of workers rallied around the country to protest proposed building laws.

CFMEU secretary John Setka said union workers were prepared to take action against the Andrews Labor government over the use of 457 visa workers and illegal immigrants on state building projects.

“You came into government here declaring that you weren’t like the federal government… we have all these jobs going on and we have all these non-union, anti-union mobs that are employed 457 visas and illegal immigrants,” Mr Setka told a large rally in Melbourne’s CBD on Tuesday.

“People might have to wait for Skyrail longer than they think because they need the cooperation of the construction unions to finish all this stuff on time.”

When asked about the union’s threats, a government spokeswoman said Victoria will support contractors and relevant unions to resolve any issues.

The CFMEU warning came as thousands of workers rallied across the country to protest against the federal government’s reintroduction of the Australian Building and Construction Commission, changes to the building code, and possible cuts to penalty rates.

Victorian Trades Hall Council Luke Hilakari said the ABCC was a “devastating piece of legislation” that put construction workers’ lives at risk.

“Last time that was introduced 330 workers were killed on the job,” he told reporters.

Mr Setka said the ABCC was an attack dog for the government, driven by zealots who hate unions and workers

He said “corrupt” companies like Boral were lobbying the government for the ABCC’s return.

Mr Setka is facing charges of blackmailing two Boral executives in 2013, but is attempting to have the charges dismissed in the Victorian Supreme Court.

Australian Industry Group chief executive Innes Willox said unions were spreading false claims about the ABCC.

“The ABCC does have an important role in stopping unions using bogus safety disputes as an industrial weapon against employers,” Mr Willox said.

By Christine McGinn