LONDON: Sugar prices fell back Thursday from a 30-year peak reached a day earlier as cyclone Yasi prepared to strike Australia, the dollar weakened and oil prices extended gains above $100, analysts said.

The price of unrefined sugar for delivery in March had on Wednesday reached 36.08 US cents a pound on the New York Board of Trade -- the highest level since 1980.

In London, a tonne of white sugar for March scored £857 on Wednesday -- the highest point since 1987.

"Amidst a welter of concern regarding potential damage caused in Australian cane growing areas by the approaching cyclone Yasi, a weaker dollar and high energy prices, sugar posted... 30 year highs yesterday," said Nick Penney, an analyst at Sucden Financial brokers.

Severe Tropical Cyclone Yasi, a top-category storm, hit the Australian coast early Thursday, the country's weather bureau said, packing destructive winds which were expected to rage for hours.

Sugar futures also benefited from a weaker dollar, which made the commodity cheaper for holders of other currencies, boosting demand.

Finally, oil's surge above $100 a barrel in recent days has increased demand for ethanol, a cheaper version of gasoline, or motor fuel, that is made using cane sugar.