Tourists have been told to vacate a 250-km stretch of Australia's southeast coast before Saturday, due to a heightened threat of bushfire -- however fuel and supply shortages are hampering the evacuation.

New South Wales' Rural Fire Service (NSW RFS) issued an order on social media late on Wednesday evening for tourists to vacate the area.

The warning predicted "the same or worse" fire conditions as those felt by the region earlier in the week, which left eight people dead and over 300 homes destroyed.

"If you are holidaying on the South Coast, particularly in the general area from Batemans's Bay to the Victorian Border ... you need to leave before this Saturday," the NSW RFS said.

"If you are planning to visit the South Coast this weekend, it is not safe. Do not be in this area on Saturday."

The South Coast is highly popular with Australian holidaymakers, especially during the Christmas period and by Thursday morning giant queues had formed of those trying to access fuel, food and water.

It is the "largest mass relocation of people out of the region that we've ever seen," NSW Minister for Transport, Andrew Constance told media sources.

"People are queueing up to get into petrol stations. You can't leave on an empty tank, because the power is off in a lot of places. We need people to be well-planned."

Prime Minister Scott Morrison urged calm and patience from all those affected and said that everything possible is being done to make the evacuation run smoothly.