Thousands of construction workers strike over federal government's ...

Major disruption has hit city centres across Australia as tens of thousands of tradies walk off the job in protest against the federal government's takeover of the construction arm of the Construction, Forestry, Mining and Energy Union (CFMEU). 

The strike started at 11am and involved construction workers but also members of the Australian Manufacturing Workers' Union, Electrical Trades Union and the plumbers' union.

CFMEU workers have gone on strike after the federal government put the construction branches into administration.(ABC News: Keana Naughton)

Workers are expected to gather in cities across the country, including Melbourne, Adelaide, Brisbane, Cairns, Canberra, Perth and Sydney, putting building projects to a standstill for the day.

Thousands of people have already gathered in Martin Place in Sydney, with some travelling from as far as Newcastle to join.

In Brisbane, union members protested at the Queens Garden Park in the CBD, blocks away from the unfinished Star Casino on the northern bank of the river.

CFMEU members at Queens Garden Park in Brisbane's CBD.(ABC News: Julius Dennis)

Thousands have also congregated outside Trades Hall in Melbourne, while 200 have rallied in Cairns outside the office of Labor Senator Nita Green.

"I have literally never been more betrayed as a worker in my life," Electrical Trades Union organiser Rob Hill said in a speech to the crowd in Cairns.

"They need to be held to account forever."

Electrical Trades Union organiser Rob Hill leads the crowd in Cairns.(ABC News: Christopher Testa)

Prime Minister Anthony Albanese warned there could be consequences for construction workers taking part in the unprotected industrial action.

"The government is not for turning and nor is the Australian public — they want to see this industry cleaned up," he said.

"They want to see good unions and good businesses getting on with their job."

Construction workers are protesting at Martin Place in Sydney.(ABC News)

The Fair Work Commission states unprotected industrial actions are unlawful and can attract penalties including disciplinary action by employers and being sued by anyone affected by the action, such as businesses who have lost money as a result.

In a statement ahead of the protests, the commission noted employers were required under law to deduct a minimum of four hours of wages from employees participating in an unprotected industrial action.

Sydneysiders urged to avoid CBD while protest unfolds

NSW Police said officers were at the unauthorised protest in Sydney, which has caused rolling road closures along Macquarie Street and Elizabeth Street, heading towards Hyde Park.

Protesters have forced the closure of streets in Sydney's CBD.(ABC News: Keana Naughton)

The public been urged to avoid that part of Sydney's CBD while the protest unfolds.

Sacked CFMEU state secretary Darren Greenfield gave an emotional speech.

"We are here today because of the rotten stinking Labor Party who we helped put into government," he said.

He accused Labor of "dirty rotten politics", and urged members to vote the party out in the next federal and state elections.

NSW Police has advised the public to stay away from the rally.(ABC News: Keana Naughton)

Ahead of the protest, NSW Premier Chris Minns told 2GB Radio the action would not affect the administration process underway.

"It's going to happen," Mr Minns said.

"There might be a last-gasp industrial action today, but nothing will change.

"It's important that the new leadership of the CFMEU be put into place."

He warned workers could open themselves up to fines for their participation.

Protesters are angry about the union being placed into administration.(ABC News: Keana Naughton)

Victorian Premier Jacinta Allan said the government would work with the companies running major projects to deal with any impacts from today's rallies.

Protests come days after ex-boss's 'fanciful' claim of government deal

The mass industrial action comes a day after the federal government rejected claims by former Victorian CFMEU boss John Setka about a secret deal to save the union from administration.

Mr Setka told Channel Seven's Spotlight program on Sunday that former workplace relations minister Tony Burke and Australian Council of Trade Unions secretary Sally McManus had agreed not to put his union into administration if he resigned. 

Thousands of construction workers have walked off the job in Melbourne.(ABC News)

Mr Setka told the program that despite his resignation on July 12, the government did not hold up its end of the deal.

But yesterday, Mr Burke's ministerial successor Murray Watt dismissed Mr Setka's version of events, calling his interview "bizarre" and labelling his claims of a secret deal "absolutely fanciful". 

Mr Setka's resignation after 12 years in the top Victorian branch job came the evening before Nine newspapers published allegations of his union's links with organised crime, corruption and bullying.

Former CFMEU Victorian boss John Setka resigned from the job the day before Nine newspapers published allegations of his union's links with organised crime, corruption and bullying.(AAP: Stefan Postles)

A few days later the CFMEU's national office placed the Victorian branch into administration. 

The federal government took action against the CFMEU nationally on Friday when Attorney-General Mark Dreyfus announced all branches of the construction arm of the union were being placed into administration.