Australian farmers were waiting to assess crop damage after heavy rains, for a second successive year, left many eastern areas flooded, inundating towns and prompting helicopter rescues.

While rains were, late on Friday local time, easing in New South Wales and Queensland, after dumping 30cm (one foot) of rain in two days in some areas, they left behind flooding which has closed four coal mines.

This year's floods, caused by rains linked to the recurrence of the La Nina weather pattern, are not seen as threatening as last year's, which killed 35 people and inundated about 30,000 houses.

Nonetheless, they have left cane farmers in Queensland, which produces most of the Australian crop, with an "anxious wait" to see the extent of the damage after waters recede, sugar industry group Canegrowers said.

In New South Wales, state agriculture officials warned that, on the north coast, "widespread flooding has caused extensive damage to agriculture industries, including sugar cane and soybean crops", besides leaving livestock stranded and flooding out some aquaculture businesses

'Making folks nervous'

The potential setback to cane in Australia, the world's third-ranked sugar exporter, was credited with helping raw sugar futures close up 2.0% at 23.94 cents a pound in New York.

And the floods were seen as behind a rise of 2.3% in New York's March cotton contract to, to a close of 96.34 cents a pound.

In Moree, the centre of the Gwydir Valley cotton industry, floodwaters have hit their highest in at least 35 years, beating levels reached exactly a year ago after Cyclone Yasi, billed as the most severe ever storm to hit the state.

"Weather in Australia is making folks nervous," Mike Stevens, the veteran Louisiana-based cotton analyst, said.

"There is a lot of talk about flooding in Australia's cotton areas."

Australia's cotton crop had been expected by official forecasters to rise by more than one-quarter this year to a record 1.1m tonnes, supporting exports of a record 979,000 tonnes.

'Absolutely unbelievable'

For grains, with the rains arriving after the end of the grains harvest, cereals farms should emerge relatively unscathed.

Indeed, the downpours may provide a benefit in boosting soil moisture conditions ahead of sowings.