A photo taken on Friday of the bushfires still burning around Sydney has been shared online by the International Space Station.

It was orbiting 269 miles, about 432 kilometres, above the Tasman Sea, news.com.au reports.

Wildfires are pictured surrounding Sydney, Australia, as the International Space Station orbited 269 miles above the Tasman Sea on Jan. 3, 2020. pic.twitter.com/XUTJLHZB8x

— Intl. Space Station (@Space_Station) January 4, 2020

The Green Wattle Creek bushfire to Sydney's southwest is one of a number of blazes that can be seen in the image. As of Saturday morning it was burning at watch and act level and remained out of control.

Sydney is home to over 5.2 million people. It’s bigger than Los Angeles. That circle barely covers the harbour. This better illustrates the extent of the urban area. pic.twitter.com/TRz9l4EV31

— [#] (@Tweetlear) January 4, 2020

Authorities fear there's been "significant damage and destruction" across NSW and Victoria overnight with dozens of buildings potentially lost as a number of bushfires continue to create emergency conditions across the two states.

NSW Rural Fire Service Commissioner Shane Fitzsimmons said last night they were starting to hear of properties alight as firefighters continued to battle extreme bushfires.

He believed property losses could run into the dozens.

"Right across these fire grounds we are increasingly getting reports of significant damage and destruction," he told the ABC.

"Some areas alone are reporting at least 15 properties alight in some locations."RFS Deputy Commissioner Rob Rogers late on Saturday night said properties were believed to be lost in the Batlow area and North Nowra, and there were also reports of properties impacted at Bundanoon in the Southern Highlands. He told ABC TV there were a lot of problems in the Snowy Mountains region, while a fire that had come across the Victorian border was threatening the southern town of Eden.

Firefighters are focused on saving what they can as a southerly change sweeps up the coast from the Victoria border and fire-generated thunderstorms worsen the situation.

Premier Gladys Berejiklian earlier warned people facing extreme bushfires "it's not safe to move, it's not safe to leave these areas".

The situation was "very volatile" with southerly winds gusting up to 80km/h as the change moved up the coast.