National COVID-19 Coordination Commission member Jane Halton told the Royal Commission into National Natural Disaster Arrangements on Wednesday Australia's supply chains had been exposed as "much more fragile than we appreciated" during the pandemic.

"This has been particularly experienced through this early stage of the pandemic," the former secretary of the Department of Health said.

"We as Australia, we sit at the bottom of the world, we are self-sufficient in a number of things, and the good news is there's plenty of food in this country, but, for example, when it comes to medical supplies, I think everyone's very familiar with the issues in respect of access to personal protective equipment, PPE, and people would no doubt be aware that we've actually had to ask a number of manufacturers to re-purpose their activities in order to produce things."

While Ms Halton said supply chains were stronger now - "I don't think people should have concern that we are about to run out of toilet paper again," she quipped - Australia still did not have a good sense of where potential pinch points were.

"It is true I think that we don't fully understand all of our supply chains and where they are potentially weak and it would certainly be of assistance, I think, if those things were much better understood," Ms Halton said.

This weakness could be exposed in the upcoming fire season, the commission heard.

Emergency Management Australia director-general Robert Cameron said there was a risk international supply chains of fire retardant could be impacted.

There are no Australian manufacturers of firefighting foam, with the product imported into the country in bulk by only one company.

Documents tendered to the royal commission on Tuesday showed there were already serious problems with this arrangement.

"Having a sole supplier for five jurisdictions has posed some issues for fire services in Australia in the 2019/20 season," a report from the National Resource Sharing Centre in January said.

"Scalability of arrangements has been a challenge due to the extraordinary demand and the competing priorities of the jurisdictions."

This shortage was exacerbated by the intensity of the fire season, the extra aerial aircraft introduced, and the "understandable desire" of jurisdictions to stockpile, the report said.

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Mr Cameron told the commission Australia needed a domestic manufacturer of firefighting foam.

"We know that Australia, while very well served by the current importers, over quite a period, it is but one importer and there's no domestic onshore manufacture of retardant," Mr Cameron said.

"We are of the view - I am of the view - that the risks inherent in that supply chain, well served as we are by that particular manufacturer and importer, the risks in the supply chain would be mitigated significantly were there to be onshore manufacture. That's probably where we should be focusing."