Brazilian sugar mills' financial strain clipped output of the sweetener this month, an industry group said Tuesday.

Mills in Brazil's center-south region, which produce more than 90% of the country's cane, processed 38.8 million metric tons of sugar cane in the first two weeks of May, 4% less than the same period last year, Unica said in a report. The mills' sugar output fell 8.4% to 1.9 million tons.

The decline was due in part to fewer mills crushing cane. There were 249 mills operating through the first half of May, compared with 268 last year.

"The number of mills in operation this year continues to be below the same period of last year, compromising the advancement of the crush," Antonio de Padua Rodrigues, Unica's technical director, said in a note.

Brazil is the world's largest producer and exporter of sugar.

From the start of the season in April through mid-May, mills produced 3.4 million tons of sugar, a decline of nearly 10% from a year earlier, and made 3.2 billion liters of ethanol, down 1.7% from the year-earlier period.