China's economic planning agency said on Tuesday it has auctioned 450,000 tonnes of reserve sugar to replenish the nation's supply in a bid to tame rising prices.

The National Development and Reform Commission (NDRC) said on its website that two batches of reserve sugar were auctioned on July 6 and Aug 5.

NDRC said earlier that it would auction some 200,000 tonnes of sugar on Aug 22.

By Aug. 12, sugar's spot prices in most parts of the country exceeded 8,000 yuan per tonne, almost double that two years ago. Reserve sugar's auction prices also hit a record high.

The steep price hike is due to shrinking production in the nation's major sugar-growing areas such as southern Guangxi Zhuang Autonomous Region, and also in the major sugar exporters such as Brazil, whose production has been disrupted by extreme weather, said Zhang Sang, an analyst with the Huatai Great Wall Futures Co.

He estimated China needs 13 million tonnes of sugar this year, leaving a shortage of more than 2 million tonnes.