BEIJING - China will raise the retail prices of gasoline and diesel starting Friday, the 10th increase and by far the largest this year, the country's top economic planner announced Thursday.

As international oil prices have increased, the retail prices of gasoline and diesel will rise by 265 yuan (about $40) and 250 yuan per ton respectively, according to the National Development and Reform Commission (NDRC).

Under the current pricing mechanism, if international crude oil prices change by more than 50 yuan per ton and remain at that level for 10 working days, the prices of refined oil products such as gasoline and diesel in China are adjusted accordingly.

The NDRC has asked major Chinese oil companies, including China National Petroleum, China Petrochemical and China National Offshore Oil, to ensure stable market pricing.

Global crude prices have increased more than 35 percent since the middle of June.

The NDRC said in a report that expectations of extended production of shale gas in the United States and rising tensions in the Middle East have combined to push up prices.

The economic planner said it would closely monitor the effects of the current pricing mechanism and make changes in response to global fluctuations.