The nation's entire coal reserves slumped to 46.69 million tons as of April 20, down 12 percent from 53 million tons in the early March, said Wang at a news conference on Tuesday. 

    The national stockpile was only sufficient for 12 days of consumption, three days fewer than the March record. Coal inventories for plants in Anhui, Chongqing and Hebei were only enough for less than a week, he said. 

    The government was working to address the shortage, he said, without giving details. 

    Coal-fired power comprises more than 70 percent electricity consumed in China, the world's second largest electricity consumer after the United States. 

    Reasons for the shortages were multi-dimensional, Wang said without elaborating. 

    The government in January froze electricity prices to prevent rising coal costs from flowing through to end users and contributing to inflation. 

    "We need to comprehensively consider the situation before adjusting power prices, to take into account the affordability to both consumers and producers," Wang said. 

    Lifting electricity prices would push up the consumer price index (CPI), which was already running high, he said. 

    China produced 569.3 million tons of coal in the first quarter this year up 14.6 percent year on year, according to the Beijing-based China Mainland Marketing Research Co.. 

    The winter storms earlier this year disrupted power supplies, prompting the country's power grid companies to lift spending on repairing and upgrading their transmission lines. 

    Rocketing domestic demand for coal, fueled by such energy-intensive industries as iron and steel, and chemical engineering pushed up prices. 

    The national crackdown on illegal coal mines as well as transportation bottlenecks also contributed to the rise. 

    The country became a net coal importer in the first quarter last year, as the government scrapped the tariff rebates for exports as well as the duties on imports in 2006, in a bid to meet domestic demand.