SYDNEY • Catastrophic conditions fuelled massive bush fires across Australia's New South Wales (NSW) state yesterday, with two blazes around Sydney burning at emergency level, while in South Australia one person was found dead in a fire zone.

Some major roads heading to the south and west from Sydney were closed for part of the day and the authorities asked people to delay travel at the start of the Christmas holiday period, warning of the unpredictability of the fires due to high winds and temperatures above 40 deg C.

A cooling but powerful wind with gusts of up to 90kmh from the south swept through the state late yesterday, lowering temperatures significantly but also creating risks that the winds could spread the flames and embers.

"Today has been an awful day," NSW Rural Fire Services (RFS) Commissioner Shane Fitzsimmons said of the conditions, which were rated "catastrophic" - the highest level of danger, meaning fires can spread rapidly and are extremely difficult to control.

He said conditions in Sydney may not have reached forecast catastrophic levels, although they did elsewhere. He said the haze from the fires that has choked the city in recent weeks might have helped cap temperatures yesterday by acting as insulation.

By early evening, six fires in the state were rated at emergency level, including two around Sydney.

"We have seen property impacted and lost. We have 3,000 firefighters and emergency services personnel out there dealing with the fires," Mr Fitzsimmons told a media conference.

Media reported one person was unaccounted for near Lithgow, a town about 140km west of Sydney where a number of properties were burnt.

Close to 100 fires were burning across NSW, and the RFS said some fires were generating their own thunderstorms. Conditions are expected to improve in the coming days before another burst of hot weather in about a week.

"We will not get on top of these fires until we get some decent rain - we have said that for weeks and months," Mr Fitzsimmons said.

No significant rainfall is expected in the next couple of months, the Bureau of Meteorology said.

The Gospers Mountain mega fire has already burned almost 460,000ha to the north-west of Sydney, and there was a risk it could join up with the Grose Valley fire in the Blue Mountains to the west of Sydney.

Evacuations were being carried out in Bargo, a town 100km south-west of Sydney on the front of a 185,000ha blaze that tore through the nearby area on Thursday.

"It's horrific, it's devastating driving around. We feel pretty isolated where we are with the roadblocks. Loved ones can't come and see us," Bargo resident Corey Cartes told Agence France-Presse.

He was told to leave two days ago, but has stayed behind to defend his property.

The death of two firefighters on Thursday night, when a tree fell on their truck as they drove through a firefront, brought the death toll from the NSW wildfires to eight since early October.

Prime Minister Scott Morrison cut short a family holiday in Hawaii, a trip that had drawn sharp criticism as the crisis deepened, and returned home last night. He will visit the RFS headquarters today.

In South Australia, the authorities said one person had been found dead, another critically injured and 15 homes destroyed by a fire in the Adelaide Hills, just 40km east of the state capital of Adelaide.

The death followed another fatality in South Australia on Friday, the result of a car crash that sparked a fire.

The authorities said fires had burned through some 40,000ha in the state and 23 firefighters suffered injuries on Friday. In Victoria, the authorities said 142 fires had started in the state since Friday, with one burning at an emergency level late yesterday afternoon.

Australia has been fighting wildfires for weeks, with blazes destroying more than 700 homes and nearly 1.2 million ha of bushland.

REUTERS, BLOOMBERG, AGENCE FRANCE-PRESSE