BEIJING, Aug. 1 (Xinhua) -- China may face electricity blackouts nationwide this year due to inadequate power coal supply, the country's power regulator said in a report released on Friday.

    According to the State Electricity Regulatory Commission (SERC), increasing coal supply pressure has forced domestic power plants to stop operation occasionally.

    The coal reserve in the country's big power plants was 43.81 million tonnes, merely enough to support 11 days of normal operations, SERC statistics showed.

    Power coal prices kept rising amid increasing demand from the country's coal-fired power plants, which supply 78 percent of the country's electricity. Prices at the Qinghuangdao coal market topped 1,065 yuan (about 155 U.S. dollars) by the end of July, up 115 percent from the same time last year.

    "A drop in coal quality has also affected the normal operation of power facilities," the report said.

    Another threat to electricity supply comes from the power grid itself. The design capacity of some power supply facilities in the country fell short of the actual demand, according to the SERC report.

    In addition, some power distribution grids were in need of equipment update, putting the national power grid at the risk of large-scale electricity cut off.

    Yu Yanshan, the SERC general office deputy head, said earlier that China was expecting a maximum daily power shortage of 10 million kw this summer.