Wildfires destroyed homes and flooding claimed the life of a man in embattled Australia on Sunday, as officials warned that last week's monster cyclone would compound economic woes.

Three major fires razed properties around the west coast city of Perth, as a volatile weather system trailing Cyclone Yasi, a top-level storm that battered Australia's Northeast coast on Thursday, continued to reek havoc.

"There have been homes destroyed but we are not sure how many at this stage," an emergency spokeswoman told AFP, describing conditions as "pretty nasty."

Local media said up to 20 houses had gone up in flames at Roleystone, a heavily wooded area on the Southern outskirts of Perth, with another out-of-control blaze on the Northern fringes forcing more than 150 evacuations.

Both were described as a threat to lives and property, with officials urging residents to "act immediately to survive" by either abandoning their home, if it was safe to do so, or preparing to defend their property from the flames.

It came as the Southeastern state of Victoria paused to mark two years since the "Black on Saturday" firestorm that claimed 173 lives and obliterated entire villages.

Some towns ravaged by the 2009 fires were also hit by Cyclone Yasi-linked flash floods overnight which forced thousands from their homes in Victoria, still reeling from last month's flooding that also swamped Queensland state.

Mildura — a city of some 50,000 residents — had a year's worth of rain dumped on it in a single day, inundating 200 homes.

"We are heading for some major problems in Victoria and this is going to strike people as really cruel, given that Victoria is about to mark the second anniversary of the devastating bushfires," said Prime Minister Julia Gillard.

A man died after his truck was swept into floodwaters as he tried to cross a swollen creek near the rural town of Wagga Wagga on Sunday, while intense rains were also forecast for Alice Springs, in Australia's red desert centre.

Yasi was one of the largest storms to ever hit Australia, and Treasurer Wayne Swan warned it would deepen economic woes brought by the Queensland floods — the recovery from which is set to cost an estimated Aus$5.6 billion ($5.6 billion).

"Even at this early stage, it's clear that severe damage was done to crops, buildings and infrastructure in affected areas," said Swan.

"The region impacted by the cyclone contributes around (Aus)$1 billion of agricultural production annually, and initial reports suggest at least half of that has been wiped out in 2011."

Tourism would also be hit, he added, with the cyclone region accounting for about five percent of Australia's tourist earnings.

Swan said devastation of sugar and banana crops would add at least 0.25 per centage points to inflation in the March quarter, on top of the 0.25 per centage points already brought by the floods.

Analysts have put the damage to Australia's agricultural sector as a result of the recent disasters at Aus$1.4 billion.

Canberra has announced a one-off tax on higher-income earners to help meet the cost of rebuilding from the floods.

But Gillard vowed not to increase the levy and said recovery from the cyclone and fresh Victoria downpours would be funded through spending cutbacks.

"There are no easy choices left now, so in making further budget cuts, there is going to be some pain around and people are going to have to recognise that," she said.

Australia's wild weather has been linked to an especially strong La Nina event, traditionally bringing torrential rains and cyclones to the vast Southern continent.