The huge deluge that swamped coal-producing Queensland state in January caused significant damage, halting mine production and cutting key transport infrastructure, according to the Treasury's latest economic round-up released on April 2.

"Contacts suggested that the loss of coal production is estimated to be between 20 million and 30 million tonnes," it said.

The government has estimated the floods, which covered an area the size of France and Germany combined and were followed by destructive Cyclone Yasi, will cut coal production by about 15 million tonnes in the March quarter alone.

But businesses expect total losses to be much higher, roughly US$8.3 billion, the report said.

The floods, which left more than 30 people dead, also had an adverse effect on the tourism industry, reducing numbers during the crisis and impacting near-term prospects.

Australian tourism is facing a range of problems including ageing infrastructure, increasing competition from Asia and the high Australian dollar.

Treasurer Wayne Swan has described the floods as the nation's costliest natural disaster ever and said they would inevitably impact growth in early 2011.

The floods are expected to weigh heavily on the national budget due to be announced on May 10, which will seek to balance the costly natural disasters against inflationary risks caused by an unprecedented Asia-driven mining boom.

Last month, Parliament approved a one-off, Aus$1.8 billion tax to help pay for the flood damage, and keep the government on track to balance the budget by 2012/13 as promised.