Despite consecutive years of bumper grain harvests, China still faces potential risks in ensuring grain security due to poor storage and huge waste, senior officials and experts warned.

It is estimated that more than 35 million metric tons of grain are wasted every year in China in storage, transportation and processing, Ren Zhengxiao, head of the State Administration of Grain, was quoted by Xinhua News Agency as saying on Sunday.

Of the total waste, 20 million tons of grain are lost due to poor storage by farmers who have not yet placed their grain on the market, according to the administration.

Currently, the amount of grain stored by local farmers accounts for around half of the country's annual grain output, Ren said.

Another 7.5 million tons of grain are wasted in storage and transport, and more than 6.5 million tons of grain are wasted in processing, he said.

Meanwhile, food valued at 200 billion yuan ($32 billion) is thrown away in China every year, he said.

The country recorded a grain output of more than 589 million tons in 2012. It was the ninth consecutive year of increased grain harvests, according to the Ministry of Agriculture.

Meanwhile, the country has experienced rising imports of grain in recent years mainly due to rapid urbanization and changes in consumer demand.

More than 260 million farmers have switched to non-agricultural jobs in cities, which may hamper the country's grain harvest, said Chen Xiwen, director of the Office of the Communist Party of China Central Committee's Leading Group on Rural Work.

The country's total grain imports, including soybeans, were more than 70 million tons last year, according to the ministry. Imports of soybeans last year totaled 58.4 million tons, the ministry said.

"For China, improving its quality of grain stocks and reducing food wastage are as important as protecting arable land," said Ren.

Statistics from the State Administration of Grain showed that one-third of China's storehouse capacity for grain is old and in poor condition.

"The country should accelerate its construction of storehouses in those major grain-producing areas where there is a great shortage in storage capacity, such as in Northeast China," said Liu Yang, a researcher in agro-product processing at the Chinese Academy of Agricultural Sciences.

Also, the country's total grain storage capacity should be enlarged in the future since great waste is caused by local farmers and small rural cooperatives that lack enough investment to improve grain storage conditions, he said.

A five-year campaign will be launched this year to repair and upgrade facilities on grain storage, improve the emergency grain supply system and reduce food waste across the country, according to the administration.