China's top economic planner and price regulator, the National Development and Reform Commission (NDRC), has vowed to punish thermal coal producers for raising prices amid the country's current electricity shortage.

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The commission warned the punishments for raising prices might include heavy fines equal to as much as five times the amount of revenues generated by the price increases.

The NDRC's warning came after it had raised the price of electricity used for industrial, commercial and agricultural purposes throughout the country's 15 provinces and municipalities last month. It took that step to encourage thermal power plants to generate more electricity.