Australia's Victoria state has shut construction sites across Melbourne following a violent protest against mandatory Covid-19 vaccines.
The protest on Monday was against a requirement for staff to prove they had received a vaccine dose to access their workplace.
Officials said some sites would be shut for up to two weeks after construction workers and other protesters clashed.
Property was damaged and police said several people were arrested.
Hundreds gathered in Melbourne for another anti-vaccination protest on Tuesday, setting off flares and reportedly throwing urine at reporters.
On Monday, riot police were deployed and reportedly used rubber bullets and pepper spray to disperse crowds.
The Victoria branch of Australia's Construction Forestry Mining and Energy Union (CFMEU) was vandalised, with glass at the front of the building smashed during Monday's clashes.
It comes following an announcement that from Thursday 23 September construction workers will be required to show proof that they have had at least one vaccine dose in order to continue to work, local media report.
The CFMEU condemned "in the strongest possible terms" the attack on its Melbourne office, where members had shown up in support of the government mandate, saying the violence occurred after the protest was "infiltrated" by right-wing groups.
Some of its members were injured during the clashes, the union said in a statement, adding that bottles were thrown at officials.
"The union will continue to defend its members' rights to work safely across Australia and we will not be intimidated from doing our job," the statement said.
In a Facebook post, the Master Builders Association of Victoria said all building and construction industry sites in metropolitan Melbourne, Geelong, Surf Coast, Ballarat and the Mitchell Shire had to close from midnight Monday.
It said this was in response to a combination of a rise in Covid-19 transmissions in the building industry and the "riots" in Melbourne.
The association added that while the construction shutdown was scheduled to last for two weeks, sites would be able to reopen earlier if lockdown measures were lifted by regional governments.
With a relatively low Covid-19 death rate, Australia has been praised for its efforts controlling the virus.
The country has so far recorded just over 87,000 cases of Covid-19, and 1,167 coronavirus-related deaths, according to the latest Johns Hopkins University data.
However, about half the population has recently been placed in lockdown due to outbreaks in the cities of Melbourne, Sydney and Canberra, with the Delta variant causing cases to rise more rapidly.