Acting prime minister Michael McCormack admits Australia "absolutely" must do more to tackle climate change as parts of the country struggle through a bushfire crisis and severe heatwave.

"I agree entirely," the Nationals leader said when asked if he thought more could be done by Australia to address climate change on Saturday.

"Yes I do," he told reporters in Wagga Wagga.

"We will have those discussions."

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However, the acting PM said climate change was not the sole cause of bushfires.

“Climate change is not the only factor that has caused these fires. There has been dry lightning strikes, there has been self-combusting piles of manure, there has been a lot of arsonists out there causing fire," he said.

Mr McCormack in November attacked "raving inner-city lunatics" for linking climate change to Australia's bushfire crisis.

Filling in as prime minister until Scott Morrison returned from a family holiday on Saturday night, he said the government's immediate priority was supporting bushfire victims.

READ MORE Man unaccounted for, houses lost near Lithgow as bushfire threat intensifies

Mr Morrison touched down back in Australia on Saturday night, after copping several days of flak for taking a holiday during the fire season.

"The important thing is we put those fires out. The important thing is we wrap our arms around those who have lost loved ones," he said.

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"The important thing is we make sure we've got the proper resourcing and address the fires as they are occurring."

Mr McCormack's comments contrast with those of Emergency Management Minister David Littleproud, who says Australia is already leading from the front on climate change and emissions reduction.

"The reality is we are trying to lead by example but the rest of the world needs to lead with us," he said on Saturday.

Mr Littleproud said Australia was committed to hitting its emissions targets under the Paris climate agreement, but would not be drawn on whether the government needed to take additional steps.

"We made our commitment for Paris and we will make sure we hit that trajectory ... we need the rest of the world to come with us," he said.

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Opposition leader Anthony Albanese said the government had been "complacent" on climate change and energy policy.

"They do not have an energy policy and dismissed the comments by former fire chiefs who they refused to meet during this difficult time," he told reporters.

Emergency Leaders for Climate Action - a coalition that includes 29 former emergency services bosses - has been hugely critical of the federal government's bushfire response and position on climate change.

Bushfires have deteriorated amid "catastrophic conditions" across NSW on Saturday, while temperatures in parts of the state soared past 45C.