A video of a firefighter in blaze-struck New South Wales unleashing on embattled Australia Prime Minister Scott Morrison has gone viral.

Dozens of blazes continue to threaten lives, leaving firefighters exhausted.

One couldn't contain his frustration and unleashed on Morrison as he drove past a Seven News camera in a fire engine.

"You from the media!" he says as he pulls up beside the 7News camera. "Tell the Prime Minister to go and get f**ked, from Nelligen." Nelligen is a village on the south coast of NSW.

"We really enjoy doing this sh*t!"

One version of the video shared to Twitter has been viewed more than 1.6 million times and racked up nearly 15,000 re-tweets.

The exhausted firefighter was later seen to have collapsed on the ground by the roadside.

"I've lost seven houses in Nelligen already and I'm not going to lose anymore," the firefighter told 7 News. 

• Australia fires: More New Zealand firefighters on their way to help battle blazes
• Kiwi farmers calling on Anzac spirit to support bushfire-hit Australian counterparts
• Kiwi firefighters set to battle Australian bushfires
• NZ and Singapore Defence Forces adding to Op Bushfire Assist
• NZ Defence firefighters on Oz bushfire front lines – ADF cites OH&S

Another firefighter also had a message for Morrison, saying he should "stand down, now".

There has been significant damage to coastal NSW towns including Nelligen, according to local media.

"A lot of damage happened ahead of the southerly front and then some different locations came under threat after the southerly," Rural Fire Service spokesman Marty Webster said on Wednesday.

"We know there has been significant impact into places like Quaama, Cobargo, Nelligen and Mogo," Webster told the Barossa Herald.

Morrison has come under fire for his leadership amid the bushfire crisis. He faced heavy criticism for going on a family holiday to Hawaii while the bushfires raged, and while visiting the NSW village of Cobargo earlier this week, residents yelled insults at him calling him an "idiot" and a "f***wit".

It's been a political nightmare for Morrison, who continues to be dogged by questions of whether his Government is doing enough to tackle climate change.

On Sunday, fire services in NSW are warning residents it's too late to leave, saying they should instead seek shelter.

Since Monday, the fires have claimed the lives of 13 people in NSW, Victoria and South Australia.