Acting on advice from the Minister for Police and Emergency Services and the Emergency Management Commissioner, Mr Andrews said late on Thursday night that the decision - a first for Victoria - would give his government special powers to deal with the bushfire crisis.

By declaring a state of disaster, emergency services can take over properties and forced evacuations can take place, having been voluntary so far, at the request of the Chief Commissioner of Police.

Upper Murray and North East residents were advised to leave on Thursday if they could but Mr Andrews said the latest move was a necessary one for residents in Towong, Alpine, Wangaratta and Mansfield shires.

Mount Buller, Mount Hotham and Mount Stirling alpine resorts have also been included in the state of disaster area.

"If you can leave, you must leave," Mr Andrews said.

"If you stay we cannot guarantee we can protect you."

IN OTHER NEWS:

Police Minister Lisa Neville said "we are using the strongest powers available to us ... heed the warnings".

The Upper Murray blaze has burnt through 120,000 hectares since Sunday and destroyed more than 15 homes.

At a community meeting in Tallangatta on Thursday, attended by about 200 people, Police Inspector Luke Kirton said "even if you are well prepared, (ask) whether you are prepared to take on something as big and ferocious as that".

Mr Andrews' call came shortly after NSW declared its third state of emergency in as many months.

With severe to extreme conditions forecast for Saturday, Premier Gladys Berejiklian on Thursday declared the week-long state of emergency would run from Friday.

NSW's first state of emergency since 2013 was declared in mid-November ahead of dangerous fire conditions, and another was implemented over Christmas.

MORE FIRE UPDATES:

A two-day statewide total fire ban begins on Friday, when very high fire danger is forecast for districts on or immediately west of the Great Dividing Range.

People near Batlow, population 1300, have been asked to leave by Thursday with the town expected to be hit by the Dunns Road fire on Friday.

"The township will not be defendable," the RFS warned residents.

Holiday-makers in the alps and between Nowra and the Victorian border were asked to be out by Friday night, causing massive traffic queues and petrol shortages.

NSW Rural Fire Service Commissioner Shane Fitzsimmons said Saturday's conditions would be at least as bad as those on New Year's Eve, which left a trail of ruined homes, businesses and utility lines.

- with AAP

VICTORIAN GOVERNMENT DECLARES A STATE OF DISASTER

Premier Daniel Andrews has declared a State of Disaster for six Local Government Areas and the Alpine Resorts after considering advice from the Minister for Police and Emergency Services and the Emergency Management Commissioner.

The Premier is satisfied there is an emergency that constitutes, or is likely to constitute, a significant and widespread danger to life or property in the following part of Victoria:

Conditions are expected to deteriorate from tomorrow and the Government's priority is the safety of Victorians.

A state of disaster:

The declaration gives the Government, through the Minister for Emergency Services, the powers and resources it needs to keep Victorians safe.

Examples of the Minister's broad power to direct and allocate government resources include:

This is the first time the Victorian Government has used these powers since they were included in the Emergency Management Act 1986 following the devastating Victorian Bushfires in 2009.

Dealing with the immediate aftermath of the fires while many fires continue to burn across the state is a significant challenge that involves all levels of government.

The government has already established a Bushfire Response and Recovery Taskforce to support communities and help them rebuild from the devastating fires still burning in the east of the state.