WASHINGTON — The U.S. Department of Agriculture said U.S. sugar processors have forfeited about 85,000 tons of sugar held as collateral against about $35 million in government loans that matured Aug. 31.

It was the first sugar forfeitures in about a decade.

The forfeitures occurred after the U.S.D.A. was able to sell only 7,118 tons of sugar to a single biofuels producer out of 99,375 tons offered in a Feedstock Flexibility Program tender last week. Sugar sold in the tender had to be pledged against loans that matured Aug. 31 and buyers had to use it in the production of biofuels.

More than 600,000 tons of sugar remains pledged as collateral for over $300 million in government loans that mature Sept. 30 and remain at “substantial risk” of forfeiture, according to the U.S.D.A.

More than 200,000 tons of domestic sugar has been removed from the market between three U.S.D.A. tenders in July and August and the forfeitures. But some in the trade estimate at least another 300,000 tons will need to be removed to avoid forfeitures at the end of September. Further, shipments from Mexico, which may enter the United States unrestricted under the North American Free Trade Agreement, were up about 75% from a year ago through July (the first 10 months of the 2012-13 marketing year).