Corn prices rose to a fresh high in the week to Wednesday, with overall demand rising and supplies remaining tight ahead of the fall harvest.

In major cities in the eastern Shandong province, where feed mills and processors have a strong presence, the average price rose about CNY60, or about 2.5%, to around CNY2,450/ton.

In the northeastern provinces of Heilongjiang, Jilin and Liaoning, as well as Inner Mongolia Autonomous Region, prices rose around 1% to CNY2,110-2,240/ton. The combined annual output of these regions accounts for about 37% of the nation's total.

Corn prices have risen more than 20% so far this year.

The nation's average wholesale corn price was CNY2,380/ton as of Aug. 3, up 0.9% from a week earlier, the National Development and Reform Commission said.

"Corn stocks with farmers in northeastern China are almost sold out, forcing traders to raise bid prices to acquire some grain," the Zhengzhou Grain Wholesale Market said in a research note.

Traders are also reluctant to sell, despite having limited inventories, as they expect prices to rise further before the harvest, it said.

China offered only 17,374 tons from reserves this week and sold 16,766 tons. The volume was sharply lower than last week's 34,665 tons and far below the weekly offers of 1.8 million tons at the beginning of the year, indicating that state inventories are very low.

However, it still isn't clear if, or when, the government will sell imported corn from reserves.

Meanwhile, the hog-to-corn price ratio, an indicator of returns from hog production, fell for the week in a row as hog prices have started falling though corn prices continued to climb, the NDRC data showed.