Sugar posted gains on Friday extending its rally to an 18-month high amid concerns that decreasing temperatures in China, the third-largest sugar producer, may have damaged cane crops.

Sugar futures for May delivery increased by 0.05 cent, or 0.4 percent, to 13.68 cents a pound on ICE Futures U.S., formerly known as the New York Board of Trade.

Sugar output from China was forecasted to drop by 1 million tons this year from the original 8 million-ton forecasted.

Sugar gained 7.5 percent this week, the highest since June and increased by 28 percent this year.