Australia's farmers believe more than 1 billion U.S. dollars could be wiped off the value of crops in the state of New South Wales (NSW) as a result of the floods that are ravaging the state, said the NSW Farmers Association on Monday.

The president of the NSW Farmers Association, Charles Armstrong said government predictions of up to 500 million AU dollars (496 million U.S. dollars) in crop losses are a significant underestimate.

"The true cost of the damage won't be known until people can get back in their paddocks and survey the damage," Armstrong told Australian Associated Press (AAP).

Armstrong said it was possible up to half of the state's 2.5 billion AU dollars (2.48 billion U.S. dollars) wheat crop could be wiped out.

"This is devastating for farmers, particularly those who have had to deal with drought the longest," he said.

"It's ironic that after seven, eight, 10 years of drought we finally had a really good forecast of a bumper harvest."

Armstrong said he had spoken with both state and federal agriculture ministers about assistance for farmers.

A spokeswoman for the Insurance Council of Australia said it was not yet possible to estimate the possible cost of the NSW floods to the insurance industry.