Australia will spend A$800 million ($516 million) to repair, retrofit and buy back homes in the flood-prone northwest of the country's largest state as the region recovers from its third inundation this year.

Clean-up efforts are underway across Australia's southeast as swollen rivers recede after the country's third bout of flooding this year. The wettest year on record for many regions is set to continue into summer after forecasters declared a rare third consecutive La Nina event, associated with wet weather.

Saying that the country needed a new way to combat flooding, Prime Minister Anthony Albanese announced on Friday around 2,000 homeowners in the flood-prone Northern Rivers region of New South Wales will be eligible for the program.

Homeowners in the most at-risk areas will be eligible for a government buyback. Others will be offered up to A$100,000 to raise homes off the ground or retrofit them against flooding.

"We need to do better on planning but we also need to do better than thinking that we can do just the same thing over and over again, because we will get the same result," he said.

Albanese said he would work closely with New South Wales Premier Dominic Perrottet to also push changes to floodplain building planning laws in Australia.

"We know that disasters are expected to become more frequent, and more severe due to climate change, and that's why we're working with the New South Wales Government to develop practical solutions to protect lives and livelihoods."

Eligibility for the program will be based on flood risk, property assessments and risk to safety

The package includes A$100 million for the state government to buy land in flood-safe areas for more development.