Communist leaders are alarmed at a jump in politically sensitive food prices, which hit China's poor majority especially hard. Authorities have ordered measures to increase supplies of pork and other basic goods.

Investigators will look into why prices of grain, vegetable oil, pork, beef, mutton, and poultry are rising so fast, the National Development and Reform Commission said on its Web site.

Food prices in June were up 7.6 percent from the same month last year, driven by a 74.6 percent jump in prices for pork, China's staple meat.

"Some industry groups have organized coordinated price rises and some companies have colluded to raise prices," the NDRC statement said. "This seriously disrupts normal price order and influences social stability."

Pork prices have risen especially quickly, but consumers also have seen the cost of other basic goods including vegetable oil and instant noodles rise.