More support from New Zealand is being sent to Australia in a bid to help extinguish the deadly bushfires raging across the continent.

Nearly 4000 firefighters were on the ground in New South Wales, with more than 140 fires burning across the state.

Rural Fire Service Commissioner Shane Fitzsimmons said they were receiving reports of "significant damage and destruction" on Saturday night.

And more evacuation orders were issued to Victorians overnight as massive blazes continued to ravage the state's east.

Dozens of fires were burning in Victoria early on Sunday, 13 of which were subject to emergency warnings, the highest alert level. Six people are missing.

Ron Mark, New Zealand's Minister of Defence, today announced additional support would be sent to help the Australian Defence Force:

• Three Royal New Zealand Air Force NH90 helicopters and crew;
• Two NZ Army Combat Engineer Sections;
• And a command element to support the ADF.

An ADF C-17 and NZDF C-130 would be deployed on a number of flights from Monday to Wednesday from Ohakea Air force Base.

The support was in addition to the latest rotation of five NZDF firefighters deployed to bolster numbers of responders on the ground.

Many of the NZDF personnel deployed were away on holiday when they were tasked with heading to Australia.

Mark said he was grateful for their willingness to help their Australian counterparts and that of the personnel's family members.

"We need to mention and thank those Defence Force spouses, partners and children whose holiday plans are being interrupted as their family members are being called back to assist our Australian cousins in their time of need," he said.

"I am truly grateful, and I thank them for their understanding and support."

The effects of the many bushfires could be seen in the North Island this afternoon, with smoke from the blazes turning the sky orange.

Police were flooded with 111 calls about the phenomenon - to the point where a statement was released asking people not to call them.

They said the calls to the were either to report the haze is present or to ask why the sky has changed colour.