The premier of New South Wales state Barry O'Farrell declared a state of emergency.
The fires have killed one man, destroyed a total of 208 homes in New South Wales state and damaged another 122 since Thursday, the Rural Fire Service said.
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The violence began after a counter-protester allegedly doused a female rally organiser with pepper spray.
As temperatures climb through the day, the warmest spots are likely to be across western parts of Northern Ireland and western Scotland.
Boris Johnson and Amber Rudd have both criticised social media giants for failing to detect and remove extremist material online.