The ministry said corn consumption was now seen 2 million tonnes lower than last month's forecast at 280 million tonnes because a huge fall in the pig herd was reducing demand for feed. African swine fever is fatal to pigs, though it doesn't harm humans.

China has said its sow herd declined by a record 23.9% in May from a year earlier, but some estimate the number to be twice that level. While demand will be lower, the country also planted less corn, the ministry said in its monthly crops report, thanks to a greater-than-expected shift in the type of crops being grown.

Beijing is encouraging less planting of corn in some areas in the far north and higher output of soybeans instead. This trend cut the estimated size of the corn crop by 920,000 tonnes to 253 million tonnes.

The ministry also said that southwestern Yunnan province continued to suffer from drought, and that both the sugar cane crop there and the sugar beet crop in Inner Mongolia were suffering from pests.