Floods have affected almost 3,000 homes in Queensland [AFP]

Heavy rains that have left at least eight people dead in the Solomon Islands are set to drench Australia's Queensland state, which has already been hit by severe flooding.

Australia's weather bureau said a downgraded tropical cyclone now over the Gulf of Carpentaria, northwest of Queensland, could form again and that another low pressure system to the north could develop into a cyclone within 48 hours.

The warnings come as river levels in some parts of Queensland began to fall on Thursday, allowing emergency workers to reach people left stranded by floods.

Residents trying to clean up from weeks of rain were warned to beware of crocodiles washed up from swollen rivers and snakes roaming flooded streets and yards.

More than 60 per cent of Queensland has been declared a disaster area with flooding affecting almost 3,000 homes.

The government has called in the army to help with rescue and recovery efforts.

Solomon deaths

On Thursday the Solomon Islands, situated to the northeast of Queensland, declared a national disaster after torrential rain and flooding killed eight people and left another 13 missing, destroying homes and bridges.

James Tora, the home affairs minister, said 12 communities on the South Pacific nation's main island of Guadalcanal had been assessed as disaster-hit.

He appealed for international assistance, with Australia and France already promising emergency aid.

Since December, flooding has also hit the Pacific island nations of Fiji, Papua New Guinea, Micronesia and the Marshall Islands, with tens of thousands of islanders abandoning their homes.