SYDNEY - A major flood warning was issued on Monday in the Australian island state of Tasmania, with people living near major rivers told to evacuate immediately.

Residents near the Derwent and Styx rivers in Tasmania's southeast were on Monday morning advised to leave immediately.

TasAlert, the state's emergency warning system, said that the Bureau of Meteorology (BoM) has issued a major flood warning for the Derwent River, with properties expected to be isolated or inundated by floodwaters by Monday afternoon.

"Floodwaters are a threat to safety," the TasAlert warning said. "Property, livestock, equipment, and crops are likely to be threatened by floodwaters."

It comes 24 hours after residents were told to prepare to evacuate amid severe weather conditions that have left much of the state without power.

Mick Lowe, executive director of the State Emergency Service (SES), told Australian Broadcasting Corporation (ABC) television that approximately half of the residents in the flood zone had evacuated within two hours of the alert being issued.

"We continue to encourage people to leave the area. Houses will become inundated and there are going to be a lot of houses in those rural communities that are going to become isolated over the next 24 to 40 hours," he said.

He said that the SES received over 300 calls for help in the 24 hours to Monday morning as strong winds caused widespread damage.

Winds exceeding 150 km per hour were recorded in the island state on Sunday night.

As of Monday morning, more than 10,000 properties were affected by power outages across the state.

The airport in Launceston, Tasmania's second-biggest city, was relying on generators for electricity on Monday morning but was still operating flights despite the strong winds.

Conditions in Tasmania are forecast to ease by Tuesday but the SES has urged people to remain cautious.