He estimated SPC will lose well over the equivalent of one million cans of 425 gram diced tomatoes because of the proposed action - a claim Mr Hefford rubbished.

"The tomatoes won't be taken out of the ground because it's too wet,"the union leader said.

Workers have been in pay negotiations with SPC's new owners since August,following Coca-Cola Amatil's sale of the company in June.

They are hoping for a zero per cent pay rise in the first year and a 1.8 per cent pay rise in the second year,with casuals to keep their existing entitlements and pay rates.

"We're talking about an hour off on Friday and workers deciding not to do overtime on the Monday,"Mr Hefford said.

"They're not asking for much,they can understand the need to make a profit,but it shouldn't be at the expense of workers."

Panic buying has seen supermarket shelves stripped of essentials,such as toilet paper and canned goods across several states.

Victorian Council of Social Service chief executive Emma King urged people to stop stockpiling goods as it disproportionately affects those on low incomes or government payments,including the sick and elderly.

"These people live week-to-week on little cash and simply don't have the disposable income to buy a trolley full of toilet paper,"she said.

Medical professionals and the state government have also said there is no need to stockpile.

AAP