The government’s main forecaster on mining and farm industries painted a grim picture of Australia's coal exports and farm produce.

Australia says the floods that have devastated its eastern states are costing the country at least $3 billion in lost farming and coal exports.

Rivers surged to record heights and put rural towns and an already waterlogged city on flood watch Friday. Residents of Brisbane sandbagged homes again as an exceptionally high tide and overnight rain threatened homes in low-lying areas of the city that was devastated by flooding last week.

The government’s main forecaster on mining and farm industries said lost coal exports were worth up to 2.5 billion Australian dollars ($2.5 billion).

The agency says farm produce - most of which is exported - will be cut by at least $500 million this fiscal year.