The evacuation orders came as communities living along 1000km of the NSW east coast endure another day of flooding rains.

As the deluge continues, the federal government is scrambling to ensure a more adequate response to the disaster after it emerged victims were largely left to fend for themselves for days.

Multiple flood warnings are current for vast swathes of NSW as heavy rain batters the state, where saturated soil and swollen rivers could lead to landslides.

State Emergency Service Assistant Commissioner Sean Kearns said there were 54 evacuation orders in place across the state and 16 evacuation warnings.

The SES received more than 2400 calls for help in the past 24 hours and undertook around 100 flood rescues, mostly in Sydney.

The east coast low that hit the Mid-North coast on Monday is moving south over the Hunter and Greater Sydney and would track into the Illawarra and South Coast on Tuesday.

“We are expecting to see widespread heavy rains today which will lead to river rises,” Mr Kearns told Sydney radio 2GB on Tuesday.

“If we do issue an evacuation order take heed of that advice.”

Meanwhile, senior economic ministers will meet to finalise further financial support to flood-ravaged communities, as thousands more defence troops prepared to arrive to assist clean-up efforts.

Stung by criticism of its response to the disaster, cabinet’s expenditure review committee will convene later on Tuesday, where flood assistance will be discussed.

Prime Minister Scott Morrison said the government was finalising the first wave of what he described as “over and above measures” – disaster funding that is outside of the existing categories of support.

Mr Morrison said the plans would be integrated alongside similar support from the NSW government.

“The Australian government will stand with those communities in the northern rivers to support them as they clean up now and in the months and years ahead,” he said.

“This is not just a flood event … this is a catastrophe on a national scale”

The prime minister described the flooding event as mind-boggling, with more than $200 million in disaster recovery payments already made since the crisis began.

As criticism from residents in flood-affected communities intensifies about a lack of federal support from ADF personnel, it’s expected the number of troops on the ground will reach 5000 by the end of the week.

Defence Minister Peter Dutton defended the timing of the ADF’s arrival, arguing many areas were inaccessible.

“It’s not just a couple of streets or a couple of towns or anything like that, it is a broad area of cultural communities,” Mr Dutton told ABC Radio on Tuesday

“Despite the magnificent work (ADF troops) have done, I think they just became overwhelmed with the scale of it.”

Dutton said ADF assistance would increase as flood waters subside.

“We need to be realistic about the situation in northern NSW. It’s actually not just a flood, as others have pointed out – this is more of a cyclone,” he said.

“There were roads that are no longer there, houses have been condemned, these are circumstances in which they’re dealing and it will take time to respond and rebuild.”

ADF troops coming into flood areas will spend the coming days helping to clear roads and fix telecommunication networks and will use helicopters to drop critical supplies to cut-off communities.

However, opposition disaster and emergency management spokesman Murray Watt said there had been a lack of government support for some of the hardest hit regions.

The SES ordered residents in multiple suburbs in Sydney’s southwest along the Georges River to evacuate overnight – some without warning.

People in Camden were told to leave on Monday night after 80mm of rain fell and the Nepean River flooded.

“If you remain in the area you may be trapped without power, water and other essential services and it may be too dangerous to rescue you,” the SES warned.

The SES later issued evacuation orders for Chipping Norton, Georges Hall, Picnic Point, Pleasure Point and Sandy Point as well as parts of Holsworthy, East Hills, Milperra, Moorebank and Warwick Farm.

Evacuation centres have been set up in Canley Vale and Menai.

People living in parts of Emu Plains, Penrith and Mulgoa in Sydney’s far west were told to prepare to evacuate.

The Bureau of Meteorology has issued a severe weather warning for damaging winds and heavy rain in Greater Sydney, the Hunter, the Illawarra, South Coast, Central Tablelands, Southern

Tablelands and parts of the Mid-North Coast, South West Slopes, Snowy Mountains and the ACT.

Intense rain could lead to dangerous and life-threatening flash-flooding with thunderstorms and six-hourly rainfall totals in excess of 150mm possible.

Damaging wind gusts peaking in excess of 90 km/h are also possible and storms are expected to continue until at least Wednesday.

Meanwhile, a 67-year-old woman and her 34-year-old son are missing after their car was found in a stormwater canal at Wentworthville in Sydney’s west.

NSW Police were alerted after the Mazda3 was found in the Cooper Creek stormwater canal on Monday afternoon.

Sydney Trains is asking commuters to avoid non-essential travel and allow extra travel time as it undertakes inspections to ensure the rail network remains safe amid the deluge.

“What we are faced with is a very serious situation on broad areas of the NSW east coast,” the BOM’s Dean Narramore said on Monday.

The BOM warnings extend to “every community and town in between and extending well inland towards the Blue Mountains, Central Tablelands, Southern Highlands and possibly Canberra,” he said.

A severe weather warning for damaging and hazardous surf is current for Hunter Coast, Sydney Coast, Illawarra Coast, Batemans Coast and Eden Coast.

Heavy rainfall over the past week has caused major flooding in the Hawkesbury-Nepean Valley.

The SES is warning river levels could rise along the Nepean and Hawkesbury rivers, potentially bringing “deep and dangerous flooding”.

Major flooding is occurring at Menangle, North Richmond, Wisemans Ferry and Putty Road.