There was "no choice" but to shut down swathes of Victoria's construction industry because of the spread of COVID-19 and low public health compliance, the state government says.
Health Minister Martin Foley on Tuesday defended a late-night decision to close down construction in locked-down Melbourne, Geelong, Ballarat, the Mitchell Shire and Surf Coast.
He said for weeks the government had been warning of high cases linked to construction sites, with outbreaks taking hold in a young and mobile workforce.
"We have also reflected on poor levels of compliance with health directions and poor levels of application of COVIDSafe principles and practices in multiple workplaces, big, small and in between," Mr Foley told reporters.
"As a result of these figures, the public health team was left with no choice but to hit the pause button and continue working with the sector over these next two weeks to improve compliance."
There are 403 cases directly linked to construction, he said, from 186 work sites.
Of those, 151 sites are in metropolitan Melbourne with 362 connected cases - included 49 people who live in regional Victoria.
An audit of about 200 construction sites on Thursday found 73 per cent were failing to comply with health directions.
The shutdown began on the same day Victoria recorded 603 new COVID-19 cases and one death.
It was the highest daily tally in the current outbreak and since August 2020.
It brings the total number of active cases in the state to 6000 and the number of death from this outbreak to 13.
The shutdown followed a violent protest outside the CFMEU's head office in the Melbourne CBD, which continued for a second day on Tuesday.
The riot squad and mounted police faced off with a hi-vis wearing crowd of mostly young men.
The CFMEU Victorian construction branch secretary John Setka described the protests as "absolutely outrageous".
"We've tried to keep our members all working and ... because of a handful of drunken idiots there's 300,000-plus workers sitting at home for at least the next two weeks," he told ABC radio on Tuesday.
An amnesty will be in place on Tuesday so that a limited number of workers can attend construction sites to shut them down safely.
The government said all sites will need to demonstrate compliance with the chief health officer's directions prior to reopening, including proof workers have had at least one dose of a vaccine before they return to work on October 5.
The Property Council of Australia said the shutdown would cost the economy $1.1 billion a week.
Opposition industry spokeswoman Bridget Vallence said the Andrews government must immediately reverse its "panicked decision".
The state's roadmap out of lockdown was released on Sunday, detailing small changes to restrictions when 80 per cent of Victorians aged over 16 have received a single vaccine dose.
Melbourne's lockdown will remain in place until 70 per cent of Victorians are double-vaccinated, a target that could be reached around October 26.
