THE worst flood in living memory was set to spread further into suburban and central Brisbane in the early hours of this morning, adding to a colossal trail of destruction and death across Queensland that continues to horrify the nation.

Thousands of homes and businesses in Brisbane and the regional city of Ipswich were already submerged by last night, and more were expected to go under as the Brisbane River kept rising ahead of an expected peak at 4am today.

The drama in Australia's third largest city unfolded as search teams in the Lockyer Valley, about 130 kilometres inland, found more victims from Monday's flash floods.
A man's body was found in a house in the devastated township of Grantham, and the remains of another man were discovered in a creek.

Later yesterday, the body of a man in his 50s was found in a car in Ipswich. His death was expected to bring the official toll in the region since Monday to 13.

The toll appears certain to rise further as teams continue searching trees, creeks and cars for bodies. Police said they held grave fears for nine people unaccounted for in the Lockyer Valley, while the number of missing was revised down to 43.

Before this week's dramatic events, the deluge in other parts of Queensland had claimed 11 lives since November 30.

Queensland's Coroner and specialist counselling teams were sent to the Toowoomba and the Lockyer Valley region yesterday as Premier Anna Bligh warned the search and rescue effort would go on for days.

''Families who are still holding out hope, some of them are likely to have their hopes tragically crushed,'' Ms Bligh said.

In the worst affected areas, search groups used special cameras to try to find any bodies inside destroyed buildings.

''Our hope is that we actually might find some survivors, but the chances of that are quite remote,'' state disaster co-ordinator Ian Stewart said.

But there was one welcome development in the Lockyer Valley, with the discovery that two people who were swept away and presumed dead had in fact survived. ''One could only describe it as a miracle based on the circumstances of how they went missing,'' said Police Commissioner Bob Atkinson. There were no further details.

Brisbane also received a small consolation last night when officials revised the expected flood peak for the Brisbane River from 5.5 metres down to 5.2 metres - just below the 1974 flood level.

But the number of properties expected to be flooded - almost 20,000 homes and 3500 businesses - and the cost of the repair bill were certain to be unprecedented. Ms Bligh said: ''The city is much bigger, much more populated and has many parts under flood that didn't even exist in 1974 ... We are still looking at an event which will cripple parts of our city.''

She said many residents of Brisbane would awake today to scenes they had ''never seen anything like in their lives''.

As darkness fell last night, large areas of the central business district were under water, as were the city's major cultural institutions lined along the river in Southbank - the State Library, the Museum of Brisbane and Gallery of Modern Art. Works on the ground floor of the Queensland Art Gallery were moved to higher floors.

Many businesses across the city and suburbs were closed, and hundreds of roads were cut.

Scores of multimillion-dollar riverfront homes and apartments were among the first to be submerged, and the number of suburbs affected by flooding was expected to reach up to 80.

In the suburb of Fairfield, water was already as high as the roofs of some houses yesterday. Similarly in Ipswich - only the roofs of homes and businesses were visible in the city centre as the Bremer River approached a peak of 19.5 metres.

By last night, power had been cut to about 115,000 properties in flood-affected areas. It was not expected to be restored until the water receded.

The rising water demolished much of central Brisbane's riverside infrastructure. Boats and pontoons were swept out to sea and raw sewage spilled into the water after treatment plants were inundated.

The waterlogged SunCorp stadium was the site of a large explosion as flooding caused fire in two transformers.

Lord Mayor Campbell Newman said council engineers would demolish Brisbane's floating 850-metre Riverwalk amid fears it would become a floating missile, sending slabs of concrete down the river.

As waters rose yesterday, three more evacuation centres opened in Brisbane, bringing the total number to five, with accommodation for more than 16,000 people.

Prime Minister Julia Gillard, who visited evacuees at Brisbane's showgrounds and stood alongside Ms Bligh as she briefed the media yesterday, said more defence force personnel and aircraft were being sent in. ''Australia is standing with you,'' Ms Gillard said.

In St Lucia, in Brisbane's west, firefighters used boats to help evacuate 100 residents from an apartment block as the rising river turned areas of the suburb into islands.

In Ipswich, as stories of looters swirled, mayor Paul Pisasale said anyone found stealing during the flood ''would be used as flood markers''.

But residents took some comfort in flood predictions being downgraded by a metre.

With more than 3000 evacuated residents hoping to survey the damage to their homes when waters recede today, Mr Pisasale warned people to take care. ''Do not rush back into your homes unless you check the electricity because a lot of people in the 1974 [floods] lost their lives because they didn't check that and got electrocuted,'' he said.

In the Western Downs town of Chinchilla, residents were told to boil water after e-coli was detected in the local supply. The town is experiencing its second episode of major flooding in 10 days.

In northern New South Wales, where flooding in the past two days has caused the evacuation of 3000 people, rescuers saved a three-week-old baby in Grafton and plucked two people to safety from the raging Clarence River.

In Victoria, heavy downpours experienced in parts of the state yesterday could cause major problems today.

Up to 170 millimetres of rain uprooted the Wimmera-Mallee pipeline in four places along the Jeparit-Rainbow Road. Flash flooding also forced the evacuation of 12 homes in Natimuk.

Communities near the Wimmera, Avoca and Loddon Rivers are expected to be hardest hit.

A 40-kilometre stretch of the Great Ocean Road, closed yesterday because of landslides, could be blocked for days, State Emergency Service spokesman Tim Wiebusch said.

Meanwhile, corporate Australia is counting the cost of the Queensland floods, which have smashed railways, flooded mines and closed factories.

Companies including Leighton, The Reject Shop, Suncorp, Asciano and Caltex updated the Australian Securities Exchange yesterday on the effect of rising waters on their businesses.

There will be some relief though for home owners with major banks set to freeze mortgage repayments for up to three months for the flood-affected.

Ms Bligh said there would be a substantial economic impact on the nation's economy. ''We are a large part of the Australian economy and we are seeing major industries catastrophically affected,'' she said.

British Prime Minister David Cameron yesterday phoned Ms Gillard and offered his sympathy to people affected by flooding in Queensland.