Border restrictions may also impact the assistance that can be provided by international and interstate personnel, with the ACT planning for a worst case scenario where it is on its own.

The NSW Rural Fire Service has warned that even during a moderate bushfire season, a COVID-19 outbreak could impact firefighting efforts in an affected area and require additional resources to be brought in.

"In the event of a high disease spread scenario with a high rate of infection, the associated loss of individuals from service will, in a moderate fire season, severely affect the ability to maintain an adequate response," an RFS document before the Royal Commission into National Natural Disaster Arrangements said.

Fire incident management activities create an ideal environment for the transmission of infectious diseases, the document said, due to confined living and working conditions, the lack of access to and use of soap and sanitisers, and the transient workforce.

RFS commissioner Rob Rogers said while there are social distancing protocols, firefighters are brought together in fairly confined spaces like base camps and staging areas.

"When you start thinking about one of those areas ... if you suddenly start getting a few people that had confirmed COVID cases then your assumption of who may be infected could be quite large," he told the commission on Wednesday.

"If we've got fires that are being managed, you could take out potentially hundreds of people, in the need to isolate those people in case they are infectious."

Mr Rogers said mitigation measures were being implemented such as significantly reducing the capacity of base camps to ensure social distancing, and restricting access to fire control and emergency operations centres.

"That's very much designed to try and ensure we minimise the likelihood of our people being exposed to it but we have to also contemplate the possibility that we could have outbreaks like that."

Senior counsel assisting the commission Dominique Hogan-Doran said the pandemic may continue through the 2020-2021 bushfire season, which may affect possible deployments of personnel and assets from interstate and overseas.

ACT Emergency Services Agency Commissioner Georgeina Whelan said planning was underway to prepare for the impact of COVID-19 restrictions on the upcoming bushfire and storm seasons.

"We are planning for the worst case scenario which is that we may not be able to rely on cross-border relationships subject to quarantine requirements, and just workforce availability," Ms Whelan said.

ACT RFS acting chief officer Rohan Scott said hygiene measures had already been introduced but further changes would be made for bigger incidents, such as deployments to a base camp being heavily regulated with quarantine measures.

"There has been some concern from volunteers that if they were to deploy to assist to another jurisdiction, what would then be the quarantine arrangements on their return from a cross-border operation," he added.

Australian Associated Press