Grieving mudslide survivors carried the bodies of loved ones for hours down washed-out mountainsides in Brazil as the death toll hit 514.

They told of entire neighbourhoods in a resort city destroyed and pleaded for food and water to reach those still isolated by the country's deadliest natural disaster in four decades.

Officials said the death toll in four towns north of Rio de Janeiro was still rising and could jump further once rescuers can reach areas cut off by Wednesday's slides. They refused to estimate how many remain missing but local reports put it in the hundreds.

After morning rains caused delays, rescuers resumed their efforts but manpower or resources had yet to reach many in Teresopolis, a mountain city of 163,000 alongside a national park that hosts a major training site for Brazil's national football team.

It holds ornate weekend homes where the wealthy of Rio escape the summer heat to enjoy horseriding and rock climbing, as well as brick or wood houses built by the poor on denuded land.

The avalanche of mud and water swept away trees and sent boulders larger than cars rumbling down the slopes, striking rich and poor alike ? though most of the toll appears to have fallen on the poor.

It is the worst natural disaster to hit Brazil since flooding and slides killed 785 people in 1967, according to the International Disaster Database, which has records of deadly natural events in Brazil since 1900.

Fernando Perfista, 31, a ranch hand, walked with friends for hours through the night, carrying the body of his 12-year-old son, the only one of his four children he had found. In the Fazenda Alpina area where he lives, Perfista said uncovered bodies still lay on the ground and the injured were left to suffer on their own because no relief had yet reached them.

He said he found his son's body buried in the mud and had to put it in a refrigerator to keep it from dogs while he went out to search without success for his other three children.

Friends helped Perfista haul the boy's body to town, where they buried him. Like the scores of other survivors standing outside a morgue in Teresopolis, he was dazed with shock.

"My children are in there, in that riverbank, under that mud," he said blankly, a hand held to his face.

Amauri Souza, who helped Perfista hike his son's body to town, said a few helicopters are reaching remote areas, but "they're only taking down the wounded".

Now, after the initial disaster, he fears another from hunger, thirst and disease if officials do not act.

"The water is rotten but people are forced to drink it. There is no food. I had meat in my house but it's all gone bad." Despite the number of deaths, the relatively low number of injured has surprised officials.

Meanwhile, in Australia, a volunteer army waded through stinking mud and drenched homes in a massive clean-up operation as floodwaters receded in Brisbane.

About 7,000 residents joined 600 military personnel in what was dubbed Salvation Saturday to shovel the muck and clean houses and businesses inundated by the Brisbane River, another casualty of weeks of flooding across the state of Queensland. Armed with mops, brooms, rubbish bags and cleaning supplies, the volunteers were bused to the areas of Brisbane most in need.

More than 30,000 homes and businesses were flooded with muddy water and officials warned some residents that their homes were so badly damaged they would need to be destroyed.

Weeks of relentless rains and flooding across Australia's northeast have left 26 people dead, with 28 others still missing.

Meanwhile, the United Nations said it will launch an emergency appeal for funds to help those affected by floods that have ravaged the east of Sri Lanka for days.