Nationals MP Barnaby Joyce has faced a barrage of criticism after suggesting two people who died in NSW bushfires "most likely" voted for the Greens.

Greens leader Richard Di Natale took to social media, ‏tweeting "how low can you go?".

"Why does it matter who the victims of this terrible fire voted for? Stop trying to shift blame and distract from your government's failures to address the climate crisis, and remember: the first duty of a government is to look after its people," he said.

How low can you go @Barnaby_Joyce? Why does it matter who the victims of this terrible fire voted for? Stop trying to shift blame and distract from your government's failures to address the climate crisis, and remember: the first duty of a government is to look after its people. pic.twitter.com/m2jd0HTZWR — Richard Di Natale (@RichardDiNatale) November 12, 2019

Greens Senator Sarah Hanson-Young tweeted the comments were "unbelievably low, even for him".

Barnaby Joyce’s sick comments about the ppl who have died in the fires being greens voters were unbelievably low, even for him. — Sarah Hanson-Young💚 (@sarahinthesen8) November 12, 2019

Labor frontbencher Kristina Keneally slammed Mr Joyce's remarks during a Senate estimates hearing.

"How does he know who they voted for and why does it matter? They're dead; they died in a bushfire. Isn't that enough?" Senator Keneally said.

Prime Minister Scott Morrison called for calm.

"There have been a lot of provocative comments made over the last few days from all sides of the debate and I find it very unhelpful," Mr Morrison told reporters in Canberra.

"The last thing that people in an urgent crisis need at the moment is hearing politicians shout at each other.

"There is a time and a place to debate controversial issues and important issues, right now it's important to focus on the needs of Australians who need our help."

AAP

My Joyce stirred controversy earlier Tuesday while blaming the minor party for increasing the threat of bushfires.

"I acknowledge that the two people who died were most likely people who voted for the Green party, so I am not going to start attacking them," he told Sky News.

"That's the last thing I want to do. What I wanted to concentrate on is the policies that we can mitigate these tragedies happening again in the future."

AAP

Mr Joyce doubled down on disputed claims the fire service had conducted insufficient hazard reduction burns this year as a result of opposition from Greens councils.

He also criticised Greens MP Adam Bandt for demanding an end to coal production.

"To make these spurious links - that a policy change would have stopped the fire - is so insulting and just completely beyond the pale," Mr Joyce said.

Mr Joyce's remarks are the latest in an increasingly bitter stoush between the Nationals and Greens over the cause of the bushfires.

On Monday, Nationals leader Michael McCormack attacked "raving inner-city lunatics" for linking climate change to the fires.

In return, the Greens labelled the deputy prime minister a "dangerous fool" who was putting lives at risk.

Greens Senator Jordon Steele-John branded major party politicians "arsonists" for supporting the coal industry.

His incendiary spray on climate policy came as catastrophic fire conditions gripped NSW.

"You are no better than a bunch of arsonists - borderline arsonists - and you should be ashamed," Senator Steele-John told the chamber.

Additional reporting: Nick Baker