Exceptional monsoon rains have caused severe flooding in parts of Australia's north-eastern state of Queensland.

Cars and livestock have been swept away over a large area around the coastal city of Townsville. Emergency crews are evacuating people on rafts.

Up to 20,000 homes could be flooded if the downpours continue, officials warn.

A dam has reached twice its capacity and water is being released to avoid putting further strain on it. More rain is expected in the coming days.

Northern Queensland has a tropical climate and experiences monsoon rain from December to April. But the current conditions in the Townsville area are rare.

"We have not been in this situation before," Queensland Premier Annastacia Palaszczuk is quoted as saying by the Australian Broadcasting Corporation (ABC).

"There has been a lot of rain falling over the Townsville catchment and some of these levels are unprecedented."

The army is helping to protect homes with sandbags.

Resident Chris Brookehouse, whose home is flooded, told ABC: "The volume of water is just incredible. Downstairs is gone, the fridge and freezer are floating. Another five or six steps and upstairs is gone too."

Meanwhile, parts of southern Australian are in the grip of a severe drought.

Bushfires are burning in the southern island state of Tasmania, and January was the hottest month on record for Australia as a whole.