Floods cover vast area of Australia's northeast

Floodwater rose across a vast area in Australia's northeast on Friday, inundating 22 towns, forcing 200,000 residents out of their homes, and closing a major sugar export port.

Flooding has already shut coal mines in Queensland state and its biggest coal export port, forcing miners such as Anglo American and Rio Tinto to slow or halt operations.

The worst flooding in about 50 years has been caused by a "La Nina" weather pattern, which cools waters in the eastern Pacific and has produced torrential rain over the past two weeks across northeast Australia.

In the southern states of Victoria and South Australia, meanwhile, soaring temperatures and tinder dry conditions have sparked bushfires.

Authorities warned of possible "catastrophic" fires if conditions worsened and holiday travellers were asked to prepare evacuation plans.

"We're asking people to have a plan, how they're going to  get to where they're going...a plan to get away...if a  bushfire happens to threaten," said South Australia rural fire chief Andrew Lawson.

Firefighters, helped by cooler temperatures, contained small fires late on Friday, but meteorologists said readings could soar again above 40 degrees Celsius (104 degrees  Fahrenheit) in the next few days.

In Queensland, authorities warned of rising health risks from floodwaters, along with the danger of crocodiles and snakes in flooded homes.

"This disaster is a long way from over," Queensland state premier Anna Bligh told reporters.

"We now have 22 towns or cities that are either substantially flooded or isolated. That represents some 200,000 people spanning an area that's bigger than the size of  France and Germany combined."

Prime Minister Julia Gillard toured the sugar city of Bundaberg, which closed its port on Friday after flood debris  was washed downstream into shipping channels and damaged  navigation beacons.

"This is a natural disaster across Queensland," Gillard said, announcing a A$1 million ($1 million) government  contribution to a flood aid appeal which now totals A$6 million.

The closure of Bundaberg has disrupted shipments of sugar from Australia, a leading world exporter. The port normally  ships about 400,000 tonnes of raw sugar annually, with three  30,000-tonne vessels due to arrive in the next few days.

"If the port is closed for only a few days it won't be a  big issue but any extended delay would cause some concern,"  said Brian Mahoney, an executive with Marybrough Sugar Factory Ltd.

The inland sea that now stretches across Queensland is  dotted with the roofs of flooded homes, islands of dry ground crowded with stranded livestock and small boats ferrying  people and emergency supplies.

Bundaberg resident Sandy Kiddle hugged Gillard as she told of seeing her house flooded.

"It was just a sea of water and I thought the beach would  never come to our house," Kiddle told Gillard at an evacuation  centre.

Emergency authorities in Queensland said the flooding was not expected to reach a peak in some areas until Sunday and  would not recede for at least a week.

Australia has endured its wettest spring on record, according to the national weather bureau, causing six river systems in Queensland to flood. Swollen rivers in New South Wales state have also caused flood damage to the wheat crop.

Possibly as much as half the Australian wheat crop, or about 10 million tonnes, has been downgraded to less than milling quality because of rain damage. That has tightened global supplies and sent prices up about 45% this year, the biggest surge since 2007.

The floods have also pushed coking coal and thermal prices sharply higher and tight markets are keeping a close eye on further disruptions. Queensland's ports have an annual coal export capacity of 225 million tonnes.

Australia is the world's biggest exporter of coking coal used for steel-making and accounts for about two-thirds of global trade. It is also the second-biggest exporter of  thermal coal used for power generation.