Cotton gained the most in almost three weeks after the worst floods in half a century damaged crops in Australia, the world’s fourth-largest exporter.

Rabobank International slashed its outlook for Australian cotton output by 8 percent, estimating the country will produce 3.95 million bales in the year ending July 31. That compares with 4 million bales forecast by the U.S. Department of Agriculture last month. Prices almost doubled in the past year as supplies trailed demand from China.

“The fundamentals are strong, said Peter Egli, the director of risk management in Chicago at Plexus Cotton Ltd., a U.K.-based merchant. ‘‘There is an absence of sellers in the market.’’

Cotton for March delivery gained 2.65 cents, or 1.9 percent, to settle at $1.4325 a pound at 2:55 p.m. on ICE Futures U.S. in New York. Earlier, prices rose by the exchange limit of 4 cents to $1.446. The gain was the most since Dec. 21, when the fiber touched a record $1.5912.

The USDA will update its crop outlook on Jan. 12. For the year started Aug. 1, the U.S. is forecast to be the largest exporter, followed by India and Uzbekistan, government data show.