Large bushfire burns near homes on Sydney outskirts


A bushfire that has burned nearly 1,000 hectares in Sydney's south-west remains out of control but has been downgraded as conditions ease and crews begin back-burning operations.

Early this morning the threat level decreased to 'watch and act, ' and then again to 'advice, ' but firefighters have urged locals to remain vigilant and have a bush fire survival plan in place.

"We had some very big fires here in 1994, we lost something like 20 homes", he said. The fire has ripped through 2500 of land in Sydney's southwest.

More than 500 firefighters from the Rural Fire Service, Fire & Rescue NSW and the Australian Defence Force attempted to contain the blaze over the weekend with help from volunteers and 11 water-bombing helicopters.

Over the weekend the blaze was declared an emergency a number of times but was downgraded to watch and act when winds dropped down to around 15 to 25 kilometres per hour.

"Firefighters are in these areas and are ready to undertake property protection if required".

The fire, which started on Saturday afternoon, has burnt more than 2400 hectares and continues to burn in towards Barden Ridge.

Once pristine bushland has been ravaged by the fires.

Aerial footage showed the flames leaping through a forested area, with thick smoke blanketing nearby suburbs and a suburban street at a near standstill as motorists tried to leave.

RFS spokesperson Greg Allan told the AAP that it's believed that believed that some houses have been damaged.

Fire investigators were still working to determine the cause of the fire, but Mr Fitzsimmons said it was most likely deliberately lit.

Conditions are expected to aid the firefighting effort on Monday, with winds about half the strength they were on Sunday.

But high temperatures remain a cause for concern, Rural Fire Service Deputy Commissioner Rob Rogers warned.

More than 200 people visited an emergency centre at Moorebank Sports Club overnight, with local hotels offering accommodation to residents unable to return to their homes, ABC said.

"Still quite a hard day ahead (on Monday)", he told the Nine Network.

Heathcote Road remains closed on Monday in both directions from Lucas Heights to Holsworthy.

"I think we've got a long way to go before we're out of the woods".

"Residents around that area should monitor the situation, take advice from firefighters in the area and know what they'll do if fire threatens", he said.