3 dead while entire towns underwater after vicious storm lashes Australia

A man stands inside an area of The Beach Club after it was damaged by severe weather, which brought strong winds and heavy rain to the east coast of Australia, at Collaroy beach in Sydney.[Photo/Agencies]

The insurance council's Campbell Fuller said many properties on the edge of the sea are left out of policies purely because they're deemed too high of a risk.

"Many insurers don't cover actions of the sea. It's a very common exclusion," he told the Australian Broadcasting Corporation (ABC) on Tuesday.

"Actions of the sea is generally not covered by most insurance policies."

Meanwhile in Tasmania, the state's Primary Industries Minister Jeremy Rockcliff said Tuesday the fallout from the floods would be "catastrophic" for the local economy, after floods swept through the entire north of the state overnight.

"I've spoken to a number of farmers, vegetable processors and the situation for them is catastrophic," Rockcliff said.

"There are farmers who have lost 200 head of stock, dairy cattle and beef cattle. Logs have smashed through houses and irrigators have a mangled mess."

Rockcliff's comments coincide with the Tasmanian government's announcement that immediate relief aid would be provided to those affected, with up to 600 U.S dollars to be given to each family to ensure they had adequate food and water supplies.

More than 100 Tasmanians have so far been evacuated by helicopter after properties became stranded and homes were left underwater.

Authorities have said the storms are the worst to have lashed northern Tasmania since 1929, in which 22 people were killed.

Prime Minister Malcolm Turnbull took to social media overnight to urge Australians in affected areas to stay indoors and avoid crossing flooded roads, saying his government would do its best to offer support to those in need.

"Our thoughts are with all those impacted by the severe weather events around the country," Turnbull tweeted, "My government stands ready to assist and support the work of emergency personnel on the ground who have been putting their lives on the line."

"Please stay away from floodwaters, do not travel through floodwaters, stay on high ground."

The worst of the weather is said to have cleared, but the clean-up is expected to take weeks, with the damage bill expected to exceed more than 100 million US dollars.