As the Woolworth's strike marked its 13th day, an alliance of union leaders have backed them.
United Workers Union members are blocking all entrances to a distribution centre in suburban Melbourne and three other sites as they strike for better conditions and pay.
While this is an ongoing dispute, focus has recently shifted to the supermarket giant's productivity framework.
The union alleges the framework uses artificial intelligence to control staff and set unrealistic working expectation, but Woolworths strongly denies that's the case.
And now more workers could be set to join the strike in solidarity if the company attempts "to break the picket line", an alliance of union leaders say.
The National Building Industry Group Union, made up of around 20 union leaders, confirmed that their 80,000 Victorian members were “on notice” to join the strike, via social media on Tuesday.
"Should Woolworths try to break the picket line, the BIG is putting all our members on notice, if the UWU members require support for the picket we will be there in large numbers at the moment's notice," the posts read.
Meanwhile, Woolworths has apologised to customers for supply disruptions and said it has taken a $50 million hit because of the action, as it continues to call on the Fair Work Commission to ban employees from blocking its distribution centres.