CANBERRA - Australian government has declared the New South Wales state flood as natural disaster after region hit by a heavy rain and flood, official said on Tuesday.

In a statement, Federal Emergency Management Minister Murray Watt said the flooding has led to a large number of evacuations throughout Metropolitan Sydney, the Hawkesbury and the Central Coast with major flood operation still ongoing.

"We have seen some these impacted communities being hit by flood for a third and fourth time in 18 months, which is extremely distressing to the residents of these communities," said the minister.

According to local officials, so far over 50,000 people affected by the flood who were shifted to safe places.

Under, the natural disaster, government has activated emergency funding support in affected areas to help the people who were displaced by the heavy flood.

"These are uncapped payments, they are demand-driven and they will be available for anyone who qualifies," Watt told ABC News.

It comes as rain continues to bucket down on Sydney and NSW today, with authorities urging residents to stay vigilant of flash flooding as rivers continue to rise, the broadcaster reported.

Meanwhile, Bureau of Meteorology, New South Wales also issued a fresh warning of more rain and flood in several areas including Tuggerah Lake, Macquarie River and Narromine river and asked people to shift evacuation centers.

"Heavy rainfall which may lead to flash flooding may develop across the Mid North Coast and southeastern areas of the Northern Tablelands later this evening, continuing through Wednesday and easing late Wednesday, said the Bureau of Meteorology.