A visit to the Wollongong Coles supermarket found some empty spaces on the shelves.

For the most part they related to a specific product from a specific supplier - such as tinned mangoes, pretzels or a certain flavour of breakfast cereal.

Other versions of the same product - such as breakfast cereal - were still on the shelves.

Unlike the COVID-19 panic-buying, there was still plenty of toilet paper on the shelves.

Coles and the United Workers Union are in the middle of an industrial dispute, which has led to the supermarket giant closing its distribution centre at Smeaton Grange for three months.

The union's logistics director Matt Toner claimed the closure of the centre had resulted in shortages of stock on Coles shelves in its Wollongong, Warrawong, Fairy Meadow and Corrimal outlets.

"It's clear the closure of one of Coles largest warehouses is causing huge strains across Coles' NSW operations as they go into the busiest period of the year," Mr Toner said.

It's a claim refuted by Coles Chief Operations Officer Matt Swindells, who said occasional items being out of stock was "normal retail".

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He said Coles had moved items out of the Smeaton Grange facility and into "pop-up" distribution centres ahead of the lock-out, which were "working very well".

Mr Swindells said if there were "systemic" issues with supply then "you would see widespread problems across thousands of products in multiple if not hundreds of shops".

"The fake news that there are gaps now as a result of the disruption of Smeaton Grange is pretty disappointing," he said.

"It's not true and, considering the year of panic buying through the pandemic that all the Coles team members have had to work through, I think it's incredibly disappointing that a tactic like that would be deployed."