Hundreds of picketing workers fighting Woolworths for better pay and conditions have delayed a warehouse reopening, leaving supermarket shelves bare.

United Workers Union members are picketing the retail giant’s distribution centre in suburban Melbourne on Monday after it announced plans to reopen.

The Dandenong South site is one of several across eastern Australia subject to industrial action since November 21.

Woolworths announced plans to reopen the Melbourne site on Sunday.

This action has involved turning away a logistics truck, and cars being used to block all entrances to the distribution centre.

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, something they say puts undue pressure on them and has a negative impact on their wellbeing.

They are also demanding better wages and an agreement that workers at different sites are paid the same amount.

The delegates claim Woolworths will close higher-paid warehouses and then open smaller ones and offer less pay.

One union delegate said workers would continue their around-the-clock protest for as long as it took to reach a resolution, with hopes it would happen before Christmas.

He said those on strike weren’t confident, claiming the supermarket giant had planned to bus in workers to the Dandenong South distribution centre on Monday.

“I’ve told my kids that Santa Claus is on strike”, the delegate said.

The disruption has caused supermarket shelves across Melbourne to be left bare, with scenes akin to the COVID-19 pandemic.

One store, on Collingwood’s Smith Street, had most of its toilet paper aisle empty 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.

No product limits were in place at the time apart from eggs, which have been rationed for months following bird flu outbreaks in NSW and Victoria.

Woolworths has been contacted for comment.