Australia's flood crisis shifted to the country's far south on Sunday, with more than 1,400 homes swamped by a record deluge as the toll mounted in the reeling northeast amid scenes of devastation.

Dozens of towns braced for unprecedented river levels in Victoria state, where emergency officials told AFP more than 1,400 homes were waterlogged and 3,500 people had fled, just days after the flooding emergency peaked in northeastern Queensland.

"I would expect that to reach 1,500 by daylight tomorrow," emergency spokesman Lachlan Quick told AFP.

"To put that in perspective it was just a few hundred during September's floods statewide, which were some of the worst we had ever experienced," Quick said, describing the volume of water as unprecedented.

Earlier reports had said 14,000 houses had been inundated.

Homes were swamped to waist height as waters swept through the southeast, levelling fences and trees and tearing up roads. There were more than 5,000 calls for help, with more than 100 rescues.

"It's shocking, devastating, heart wrenching," said Charlton resident Peter Gretgrix. "It's just total devastation, some of the shops in the lowish area are just a mess, windows smashed out, it's terrible."

"I've never seen anything like it, (and) I'm 57," he added.

Devastated by the worst wildfires in Australia's history which killed 173 people just two years ago, parts of Victoria were now facing once-in-a-century flooding, with some towns having never experienced such inundation.

Soldiers were helping people evacuate from their homes while desperate sandbagging was under way in a number of towns, where a season's worth of rain had fallen in just one or two days, completely submerging some river gauges.

It follows a six-week crisis in Queensland, where floodwaters swallowed an area the size of France and Germany combined, culminating in the swamping last week of Brisbane, Australia's third largest city, and utter devastation of towns to its west.

Experts have linked Australia's downpours to an especially strong La Nina weather pattern bringing cooler water temperatures and exacerbating the traditional tropical cyclone season. Five of the nation's seven states and territories have seen flooding since January 1.

The Queensland death toll climbed to 18 since January 10 on Sunday, with the discovery of two bodies in the ruined Lockyer Valley -- a middle-aged man under debris near a creek and an elderly woman in her Grantham home.

Queensland Premier Anna Bligh said the house was so damaged police found the woman's body on only their third search of the rubble. Debris was piled three metres high, three metres wide and 100 metres long in the shattered town.

Residents gathered at the Murphy's Creek pub, one of few buildings still standing, to mourn the dead and pray for 14 people still missing -- the first chance for many in the tight-knit community to grieve with neighbours and friends.

"There are going to be neighbours that don't return home after this aftermath, families that don't return, there's going to be empty desks at schools," said local MP Scott Buchholz.

"Words really cannot express what the people of the Lockyer Valley are feeling at the moment."

Soldiers and police combed through buildings and fields in the search for bodies in the Lockyer Valley, where shipping containers were to provide temporary shelter for those whose homes were swept away.

As waters receded in Queensland, Bligh said the full scale of destruction was emerging, with the number of flooded homes and evacuations doubling in the past week and the number of properties affected by the waters trebling across an area with a population of 2.1 million.

She warned people to stay out of floodwaters where possible, describing them as a "toxic" soup of rotting animal corpses and food, chemicals and debris.

Treasurer Wayne Swan toured the ravaged Brisbane suburb of Rocklea with friends hit by the disaster as the federal and Queensland governments pledged Aus$10 million ($9.86 million) each to the relief fund, which has now raised more than Aus$84 million.

"In terms of cost it's far too early to evaluate," Swan told AFP of the damage bill.

"The priority is to provide immediate relief with emergency payments to the people affected.

"There is certainly a huge impact in terms of tourism, in terms of the export of resources, especially coal, in terms of small businesses. But it's too early to say how much."

Tennis stars including Roger Federer and Rafael Nadal drew sellout crowds to a "Rally for Relief" fundraiser for flood victims in Melbourne on Sunday, with a cricket charity day and major concerts also planned.