About 65 workers have been indefinitely locked out of Parmalat's yoghurt making factory in Victoria after union negotiations for a new pay deal curdled.
The Australian Manufacturing Workers Union has slammed the dairy giant for the "extreme and outrageous" action that comes after six months of enterprise agreement negotiations.
The lock out also followed a four-hour protected industrial action stoppage of work that began at 3am on Wednesday.
"The workers are simply exercising a legal right to take protected industrial action in response to the company's efforts to attack their permanent jobs and their wages and conditions," said AMWU National Food Secretary Tom Hale said in a statement.
Mr Hale says Parmalat is following the lead of other corporations who are attempting to evade Australia's industrial relations system by "destroying" existing enterprise agreements and imposing "substandard" agreements.
A Parmalat spokeswoman says the factory will remain closed until further notice.
"Parmalat is disappointed the AMWU and CEPU has decided to commence industrial action in light of the six months of good faith negotiations, which Parmalat has participated in to date," she said in a statement.
"As a result, we have had to make the tough decision to close the site indefinitely."
The unions are due to meet with Parmlat on Thursday morning for further talks.