United Workers Union members are striking at the retail giant's distribution centre in suburban Melbourne after it announced plans to reopen.
The strike action has left supermarket shelves across Victoria empty as workers block access to and from the Dandenong South distribution centre.
The distribution centre is one of several across eastern Australia subject to industrial action since November 21.
Woolworths announced plans to reopen the Melbourne warehouse on Sunday with other workers from the centre to be brought in.
But the striking group on Monday blockaded the site, turning away a logistics truck and blocking all entrances to the distribution centre with cars.
Food and grocery shortages are expected to continue after the union refused to provide assurance for the safe passage of workers looking to return to work at the Dandenong site, the grocery giant said.
"As long as they continue to block access to our site, our customers will continue to face shortages on shelves in Victoria," a Woolworths spokesperson said.
"We call on the union to do the right thing and let us re-open this site.
"Their members at the site have every right to take industrial action, but it's not right to stop people working who want to work, and customers being able to access their essential food and grocery products in our supermarkets."
A union says it will strike for as long as it takes until Woolworths addresses worker concerns. (Diego Fedele/AAP PHOTOS)
Talks between the company and the union resumed on Monday.
The disruption has caused supermarket shelves across Melbourne to be left bare, with scenes reminiscent of the COVID-19 pandemic.
One store, on Collingwood's Smith Street, had most of its toilet paper aisle emptied along with large portions of its bread and fridge sections.
In late-November, Woolworths insisted all stores were still receiving regular stock deliveries, but some were getting their goods less frequently than previously scheduled.
The action is limiting the availability of items such as nappies, toilet paper and drinks for customers across Woolworth's Victorian supermarkets.
No product limits are in place apart from eggs, which have been rationed for months following bird flu outbreaks in NSW and Victoria.
Workers are protesting against unrealistic performance expectations and unsafe work practices. (Melissa Meehan/AAP PHOTOS)
United Workers Union National secretary Tim Kennedy said despite "aggressive US-style industrial relations tactics" it seemed that after 12 days of negotiations Woolworths was showing signs of understanding their workers' claims.
"Today's negotiations show Woolworths the way they should be resolving this issue – by talking with and listening to their workers," Mr Kennedy said.
"There's no doubt we've made some progress today ... we think there is an agreement to be made if Woolworths steps forward to fix it."
Union delegates at the scene told AAP the workers were protesting against unrealistic performance expectations, which they claim have led to frequent injuries.
The expectations allocate workers a certain time for a task, then ranks their performance out of 100, which they say puts undue pressure on them and has a negative impact on wellbeing.
They are demanding better wages and an agreement workers at different sites are paid the same amount.
The delegates claimed Woolworths would close higher-paid warehouses and open smaller ones and offer less pay.
