Australian firefighters battled high winds and hot temperatures as they worked through Monday night in a bid to stop three large bushfires from merging into one spanning hundreds of kilometres in the state of New South Wales.
Firefighters are still backburning in an attempt to contain major fires in the Blue Mountains - but feat the crisis will worsen over the next few days.
The Rural Fire Service has called the bushfire threat an "unparalleled" emergency and warns if fires at Springwood, Mount Victoria and Lithgow join up, they could stretch hundreds of kilometres.
Several townships are under threat from bushfires that worsened across New South Wales late on Monday and emergency warnings remain in place for two major fires, the ABC reports.
The Springwood blaze has again been upgraded after flaring up in the afternoon and Rural Fire Service Commissioner Shane Fitzsimmons says dozens of homes around Faulconbridge are under threat. He said people living in those communities should seek shelter.
The emergency warning for the State Main fire near Lithgow was likely to remain in place for some time because conditions are so volatile.
More than 200 houses have already been lost in the fires that have raged west of Sydney since Thursday.
Commissioner Fitzsimmons said firefighters are taking "considered" but risky moves to strengthen containment lines around the massive State Mine fire in Lithgow that flanks the mountains' northwest side, AAP reports.
Firefighters have successfully conducted backburning along more than 20 kilometres of Bells Line of Road.
The commissioner also moved to allay fears of mass evacuations across the mountains after warning on Sunday that populated areas like Katoomba and Leura could be affected.
"We are not planning an exodus of the Blue Mountains but what I would say is, if you don't need to be in the Blue Mountains, don't go there."
Residents in the tiny township of Bell were on Monday again urged to evacuate ahead of temperatures in the mid-30s, low humidity and winds about 25km/h.
A state of emergency declared on Sunday gives authorities the power to force evacuations and destroy buildings that pose a danger, but those powers have not yet been used.
The Australian government has pledged its support to residents who have had their homes and possessions destroyed.
Air quality warnings have been issued for Sydney. Newcastle airport has been closed and some domestic flights have been affected at Sydney airport as a result of the fires.
Meanwhile, an 11-year-old boy has been charged with lighting two fires in the Port Stephens area, north of Sydney last week, one of which destroyed property. Police say a grass fire and a blazing bush were deliberately lit. One of the blazes turned into a firestorm destroying sheds and burning more than 5000 hectares of bushland.
NZ offers help
New Zealand Prime Minister John Key says he telephoned New South Wales Premier Barry O'Farrell on Monday to offer help to fight the bushfires.
Mr Key says Mr O'Farrell told him the situation was serious and he would not hesitate to call for assistance if needed. Mr Key says it is likely personnel from New Zealand would be sent at some stage.
Dr Owen Price, a senior research fellow at the Centre for Environmental Risk Management of Bushfires at the University of Wollongong, says there is a risk that a combined fire could produce so much energy it could create its own weather conditions.
Firestorm
"You can get these conditions, what you call a pyrocumulus, where a fire is producing so much energy it punches up through the troposphere a huge plume of smoke, essentially creating a thunderstorm with lots and lots of energy in it," he said.
"Then it starts to suck in air from all around, so there's more oxygen and it feeds back on itself so the fire behaviour goes really extreme.
"Unfortunately under those conditions when it's creating its own weather you can get things like tornados occurring.
"If two big fires coalesce together they're sort of pooling their energy together, so you can get feedback that makes them even more intense."
Dr Price says fires that serious can become impossible to fight.
But he also says the Blue Mountains fires could join up without necessarily getting much worse.
"It's not a given that if these two fires will meet that that's what they will do, they could just continue the way they're going. But there's a risk," he said.
