Sydney, Jul 4 (IANS): Floods triggered by heavy rainfall across Australia's southeast coast since last week has once again inundated Sydney and large parts of New South Wales (NSW) state, triggering the evacuation of thousands of residents.

NSW Premier Dominic Perrottet addressed the public on Monday, urging residents in affected areas to follow emergency instructions, reports Xinhua news agency.

"I want to continue to ask people to follow the instructions of the State Emergency Service (SES). If there is an evacuation warning in place, please get ready to evacuate. If there is an evacuation order in place, please leave immediately."

He said the NSW SES have received 1,593 requests for assistance overnight to Monday morning, and during the same time SES workers have performed 83 flood rescues.

Across the state and in Sydney, there are currently 70 evacuation orders in place affecting over 32,000 people.

Seven emergency evacuation centres have been established in the worst affected areas of the state.

Rain and storm conditions are forecast to continue before easing on Tuesday.

The Bureau of Meteorology (BoM) said parts of the state would receive an additional 50 to 100 mm of rainfall, which could prompt further flash flooding.

The sudden flooding is in part due to the overflow of the state's major dams which have been at 100 per cent capacity due to Australia's historically wet summer.

Emergency Management Minister Murray Watt said the unprecedented and unrelenting floods were a "very serious situation" and were further evidence to the lived reality of climate change in Australia.

"The process from here is that the NSW government needs to formally declare a disaster. We are expecting that will happen pretty soon and that will trigger a whole range of federal and state government support," Watt told national broadcaster ABC News on Monday morning.