In pictures: Sydney bushfires

Three thousand firefighters are battling 70 bushfires around the Australian city of Sydney. Homes have already been destroyed and more are threatened.

Thirty of the fires flared up within an hour on Wednesday, causing plumes of smoke

Hot and dry conditions are hampering efforts to douse dozens of fires

Residents have been evacuated from the areas most in danger

Specially equipped helicopters are being used to water bomb the flames

Firefighters take on water where they can in the desperate battle

Flames are tearing through bush land which is tinder dry after months of drought.

Heavy smoke has blanketed parts of the city and brought the smell of wood smoke to city streets

But despite frantic efforts 20 houses have been destroyed, and officials fear there is more to come.