In updates, the NSW RFS repeatedly delivered the same blunt advice to those who had not evacuated at-risk areas: "It is too late to leave. Seek shelter as the fire approaches."

Residents used social media to post photos of the sky turning black and red from the smoke and glare of the fires, including in the Victorian town of Mallacoota, where around 1,000 people were evacuated by sea on Friday.

The first of those evacuees arrived near Melbourne on Saturday morning after a 20-hour journey by boat and a second ship with about 1,000 people landed in the afternoon.

The federal government announced an unprecedented call up of army reservists to support firefighters as well other resources including a third navy ship equipped for disaster and humanitarian relief.

Andy Gillham, the incident controller in the Victorian town of Bairnsdale, said the area had avoided the worst of the fires on Saturday but stressed this was an exceptional fire season.

"In a normal year, we would start to see the fire season kick off in a big way around early January and we're already up towards a million hectares of burnt country. This is a marathon event and we expect to be busy managing these fires for at least the next eight weeks," he said.

- Reuters