As Australia faces its worst bushfire season in living memory, Prime Minister Scott Morrison has been fielding calls to do more for the tens of thousands of volunteer firefighters across the nation facing exhaustion and financial loss for protecting their communities.

Now he's ordered the heads of commonwealth departments and federal agencies to boost paid leave for public sector volunteers, so they don't have to dip into their own entitlements to battle blazes.

"We're helping get more boots on the ground and giving people who've been out there for weeks some relief," Mr Morrison said.

Under the change, the public sector workers will get at least 20 working days paid leave, or 28 calendar days, if they volunteer for fire fighting efforts.

To date, commonwealth employees had ad hoc volunteer leave arrangements.

This brings their entitlements into line with arrangements offered to Australian Defence Force reservists.

There's about 150,000 Australian public service workers, including staff at Australian Border Force, Medicare, Centrelink and various federal departments around the country.

The number who volunteer for fire fighting is not clear, but it's expected to be at least in the thousands.

"They are involved in their local brigades, some of them, " Mr Morrison told reporters in Adelaide.

"This will enable them to be able to commit more time in their brigades, and relieve ... small and regional towns that draw the volunteers from their own self-employed arrangements, or small businesses for whom the continued support to have their volunteers out fighting fires and not working in their businesses is becoming very strained."

Mr Morrison also called on large employers to follow the government's lead on volunteer leave arrangements, to ease the load on self-employed and small businesses.

And he made clear he expects non-commonwealth government employees like NBN Co and Australia Post to follow suit.

There are about 210,000 volunteer firefighters around the country.

The federal directive comes amid heightened debate in NSW over support for volunteer firefighters who have been working on multiple blazes for weeks, risking their lives and livelihoods.

The Volunteer Fire Fighters Association is calling for a formalised system to compensate for out-of-pocket expenses, such as petrol costs, and other compensation.

"This fire season's potentially going to go on for a while, people are going to be out of pocket, so it wouldn't hurt the government to put their hand in their pocket ... and help these people out," president Mick Holton told AAP on Tuesday.

But NSW Rural Fire Service Commissioner Shane Fitzsimmons hit back, saying volunteer firefighters don't want payment.

"That's absolutely the sentiment that I'm getting loud and clear, everywhere I go."

Mr Fitzsimmons said he's in regular discussions with the prime minister, NSW premier and NSW emergency services minister about hardship arrangements.

Federal opposition leader Anthony Albanese said the former Labor government led by Paul Keating in 1994 made an ex gratia payment to volunteer firefighters who had been in the field for more than seven days.

"People who are fighting fires, not for days or weeks but for months, still need to put food on the table for their families, still need to pay their rent and mortgages," he said in Blue Mountains on Tuesday.

Australian Associated Press