The Beijing Grain Bureau has worked out a color-coded alert system to coordinate work by government agencies in the event of a food and edible oil emergency.

The four-stage system starts from the premise that this city of 16 million produces only 10 percent of its food consumption.

The lowest-status alarm is blue, followed by yellow, orange and red as emergencies intensify.

The blue alert will be activated if food shortage is reported at less than 50 percent of the surveillance points in a district.

The alert will turn to yellow if there is a shortage of food at more than half of the surveillance points in a district.

Both levels can lead to market fluctuations in larger areas. Some emergency responses must be implemented, the plan says.

Orange signifies a "severe" risk, meaning more than two of the city's 18 districts and counties face a grain shortage. The grain bureau should coordinate with finance, commerce, health, agricultural bank, grain enterprises, transportation and public security agencies to take concerted efforts to ensure the grain supply and restrain prices.

Red means an "especially severe" nationwide grain shortage, a situation that requires the intervention of central authorities.

The supply of food and oil, crucial to residents' daily life, is vulnerable to a range of factors, the grain bureau said, adding that it has become more difficult for China to significantly increase grain output.

China, a country that feeds one fifth of the world population with just seven percent of the world's arable land, has been hit by a series of natural disasters this year.

Drought since autumn has affected Sichuan, Chongqing in southwest China and Liaoning in northeast China.

In east China's Shandong province, which accounts for one-tenth of the country's total grain output, 3.33 million hectares of winter wheat has withered and a further 233,000 hectares were not even planted because of the continuing drought.

But the State Grain and Oil Information Center predicted the country's grain output would increase for the third consecutive year to more than 490 million tons this year.

The center slightly raised its 2006 maize, wheat and rice production forecasts. Meanwhile, the soybean forecast was cut by 400,000 tons to 15.5 million tons.