* Hundreds of fires ablaze across Australia's east coast
* Fresh fires ignite in Victoria state
* Hazardous smoke blankets Sydney, children urged to stay inside
* PM Scott Morrison dismisses links to climate change (Adds details on Victoria fires, power outage)
By Colin Packham
SYDNEY, Nov 21 (Reuters) - Firefighters battled hundreds of bushfires across Australia on Thursday as scores of blazes sprang up in new locations, triggering warnings that it was too late for some residents to evacuate.
As Thick smoke blanketed the most populous city of Sydney for a third day, residents were urged to keep children indoors, stepping up pressure on Prime Minister Scott Morrison to tackle climate change.
By early afternoon, dozens of fires were burning across the southeastern state of Victoria and temperatures of 40.9 Celsius (105.6 F) in Melbourne, its capital, matched the hottest day on record in 1894, Australia's weather bureau said.
Authorities warned residents of towns about 50 km (31 miles) north of Ballarat, the state's third largest city, that it was too late for them to evacuate safely.
"You are in danger, act now to protect yourself," fire authorities said in an alert. "It is too late to leave. The safest option is to take shelter indoors immediately."
Blazes across several states have endangered thousands of people, killing at least four people this month, burning about 2.5 million acres (1 million hectares) of farmland and bush and destroying more than 400 homes.
The early arrival and severity of the fires in the southern hemisphere spring follows three years of drought that experts have linked to climate change and which have left bushland tinder-dry.
With 10 days remaining to the official start of summer, extreme temperatures and high winds have sparked wildfires in new areas, even as firefighters tracked the crisis across the mainland, the Northern Territory and the island of Tasmania.
In Victoria, power to more than 100,000 homes was knocked out amid lightning strikes and strong, gusty winds of more than 110 kph (68 mph) that knocked tree branches into power lines, ahead of a cool change expected to bring relief in the evening.
The extensive damage was likely to leave some customers without power through the night as utilities worked to restore networks and fix downed powerlines, a spokeswoman for power provider Ausnet said.
State authorities issued its first Code Red alert in a decade, signifying the worst possible bushfire conditions, warning that should a fire start it would be fast moving, unpredictable and probably uncontrollable.
In the state of New South Wales, strong winds blew smoke from 60 fires still burning over much of Sydney, shrouding the harbour city and its famous landmarks in thick smog.
The state imposed tough new water curbs in Sydney from Dec. 10, when a key dam is expected to be down to 45% capacity. Residents face fines if they use hoses to water their gardens and wash their cars.
CLIMATE POLITICS
The unrelenting conditions have sharpened attention on the climate change policies of Prime Minister Scott Morrison, who rejected any link.
"Climate change is a global phenomenon, and we're doing our bit as part of the response to climate change," Morrison told ABC radio.
"To suggest that, with just 1.3% of global emissions, that Australia doing something differently – more or less – would have changed the fire outcome this season, I don't think that stands up to any credible scientific evidence at all."
Morrison's conservative government has committed to the Paris Agreement for a cut in emissions from 26% to 28% by 2030, versus 2005 levels. Critics say current projections suggest it will miss that target and have urged remedial steps.
($1=1.4723 Australian dollars)